IN THE SUPREME COURT OF THE STATE OF KANSAS
No. 96,681
STATE OF KANSAS,
Appellee,
v.
RANDY J. JOHNSON,
Appellant.
SYLLABUS BY THE COURT
1. K.S.A. 22-3212(g) authorizes a broad array of sanctions for violations of discovery orders in criminal cases, including permitting the discovery or inspection of materials not previously disclosed, granting a continuance, prohibiting the party from introducing into evidence the material not disclosed, or entering such other order as the court deems just.
2. A trial court's denial of a motion seeking to exclude the testimony of a witness who violated a discovery order in a criminal case is reviewed under an abuse of discretion standard if due process rights are not implicated by the violation.
3. Low intelligence does not preclude a finding that an accused knowingly and voluntarily waived rights under Miranda v. Arizona, 384 U.S. 436, 444, 16 L. Ed. 2d 694, 86 S. Ct. 1602, reh. denied 385 U.S. 890 (1966). A waiver may be knowing, as defined by constitutional requirements, if the circumstances indicate the accused understands his or her constitutional rights and the consequences of waiving or asserting those rights. A waiver may be voluntary if law enforcement officers do not exploit the accused's low intelligence or otherwise coerce the waiver.
4. A party who does not object to the admission of testimony regarding a witness' prior consistent statements fails to preserve an argument for appeal regarding a claim that the evidence was prejudicial.
5. A sentence to any term within the range stated in a Kansas sentencing guidelines presumptive grid block does not violate Cunningham v. California, 549 U.S. 270, 166 L. Ed. 2d 856, 127 S. Ct. 856 (2007), or Apprendi v. New Jersey, 530 U.S. 466, 490, 147 L. Ed. 2d 435, 120 S. Ct. 2348 (2000).
6. Under K.S.A. 21-4721(c)(1), an appellate court is without jurisdiction to consider a challenge to a presumptive sentence, even if that sentence is to the highest term in a presumptive grid block.
7. A sentencing judge assessing fees to reimburse the State Board of Indigents' Defense Services under K.S.A. 22-4513 must consider on the record at the time of assessment the financial resources of the defendant and the nature of the burden that payment of the fees will impose. If the judge did not make these findings, the attorney fees imposed under K.S.A. 22-4513 must be vacated and the case must be remanded for consideration of the defendant's financial condition before such fees may be imposed under the statute.
Appeal from Douglas district court; MICHAEL J. MALONE, judge. Opinion filed August 1, 2008. Affirmed in part, dismissed in part, vacated in part, and remanded with directions.
Kari R. Nelson, of Kansas Appellate Defender Office, argued the cause, and Matthew J. Edge, of the same office, was on the brief for appellant.
Jared S. Maag, deputy solicitor general, and Ann L. Smith, of Lenexa, argued the cause, and Charles Branson, district attorney, and Paul J. Morrison, attorney general, were with them on the briefs for appellee.
The opinion of the court was delivered by
LUCKERT, J.: Raising an issue of first impression, Randy J. Johnson argues his consecutive sentences for the longest prison term stated in a Kansas sentencing guidelines presumptive grid block are unconstitutional in light of the holding in Cunningham v. California, 549 U.S. 270, 166 L. Ed. 2d 856, 127 S. Ct. 856 (2007), which is based upon Apprendi v. New Jersey, 530 U.S. 466, 490, 147 L. Ed. 2d 435, 120 S. Ct. 2348 (2000). He argues the only term which can constitutionally be applied is the middle term in the grid block because the factors justifying the longer term were not presented to the jury or proved beyond a reasonable doubt. We reject his argument because K.S.A. 21-4704(e)(1) does not require judicial fact-finding and grants a sentencing judge discretion to impose any of the three prison terms stated in the grid block. Consequently, Johnson's sentences are a statutorily and constitutionally permissible presumptive sentences which cannot be appealed. K.S.A. 21-4721(c)(1).
Before considering that question, we will address three challenges that Johnson presents as attacks on his convictions for four counts of attempted second-degree murder. We reject his arguments and conclude: (1) The trial court did not abuse its discretion by admitting the testimony of the State's expert witness even though the witness violated discovery orders, (2) Johnson's statement to law enforcement officers was freely and voluntarily given, and (3) the issue whether Johnson was prejudiced by the introduction of witnesses' consistent statements prior to the testimony of the witnesses was not properly preserved for appeal because there was no contemporaneous objection.
Finally, Johnson raises an additional sentencing issue regarding whether the sentencing judge erred by ordering him to reimburse the State Board of Indigents' Defense Services (BIDS) for attorney fees without first considering his ability to pay and the financial burden the payment will impose. Because the judge failed to make specific findings as required by K.S.A. 22-4513 and State v. Robinson, 281 Kan. 538, 132 P.3d 934 (2006), we vacate the attorney fees order and remand for appropriate findings.
Facts
On December 21, 2004, Johnson and two companions attended a party at the Boardwalk Apartments in Lawrence. As Johnson and his companions left the party and exited the apartment building, four individuals on a second-floor balcony confronted them about noise from the party. Johnson and one of his companions stood near the apartment building and argued with those people on the balcony. As the arguing escalated, Johnson pulled out a gun and shot toward the balcony, injuring three people. After the shots were fired, Johnson and his companions jumped in a car and, as they drove off, Johnson admitted, "My fault, dog."
Officers, who had a description of the car and the car's license tag number, stopped Johnson and the others just a few blocks from the crime scene and ordered them out of the car. Johnson exited the passenger side of the back seat by sliding onto the ground. He was handcuffed and patted down for weapons. When officers rolled Johnson onto his side, they saw a brass shell casing lying on the ground under him. Officers searched the car's interior and found a revolver and five spent brass shell casings. Subsequently, a ballistics test linked the revolver to two bullets recovered at the apartment complex.
The arresting officers noticed that Johnson smelled of alcohol and was unsteady on his feet; additionally, his speech was slurred, garbled, and difficult to understand. It was explained at trial that Johnson had smoked marijuana and consumed a significant quantity of beer and brandy.
Officers decided not to interview Johnson "because of his impaired state" and moved him to the jail for the night. The next morning, two detectives went to the jail to interrogate Johnson. Detective Warren Burket testified that there was no indication that Johnson would have trouble understanding their questions. After being given the warnings required by Miranda v. Arizona, 384 U.S. 436, 444, 16 L. Ed. 2d 694, 86 S. Ct. 1602, reh. denied 385 U.S. 890 (1966), Johnson gave a chronological description of the previous evening's events. He admitted that the gun in the car belonged to him and that he had fired it to protect one of his companions and to scare the individuals on the apartment complex balcony.
The State ultimately charged Johnson with four counts of attempted second-degree murder. Before trial the defense filed several motions to suppress Johnson's statements; all were denied. Consequently, at trial, a detective testified regarding his statements, including his admission that he was the shooter. In addition, there was other evidence linking Johnson to the shooting, including his admission to his companions, testimony of several eyewitnesses who identified him as the shooter, and ballistics tests that linked his gun to the shooting.
With no dispute regarding identity, the focal point of the trial was Johnson's defense of mental disease or defect. Defense counsel hired an expert witness, psychologist David Mouille, Ph.D., to examine Johnson. To counter, the State also retained an expert witness, psychologist Gerald Vandenberg, Ph.D. After the experts examined Johnson, the defense objected to the endorsement of Dr. Vandenberg and filed motions seeking to exclude his testimony because Dr. Vandenberg had violated discovery orders. The trial court allowed Dr. Vandenberg to testify.
The experts agreed that Johnson's intellectual capabilities were limited but disagreed as to whether Johnson had a mental disease or defect that prevented him from forming intent. To measure Johnson's intellectual capabilities, Dr. Mouille conducted I.Q. testing on Johnson, which Dr. Vandenberg "borrowed." Thus, the undisputed evidence established that Johnson's overall I.Q. is 80, which falls at the "cusp of the low average range, 80 to 89."
After conducting interviews with Johnson and performing several standardized psychological tests, Dr. Mouille concluded Johnson probably had suffered a brain injury, a conclusion he felt was supported by Johnson's mother who reported that her son twice suffered some type of injury as a young child. In addition, Dr. Mouille rated Johnson's adaptive behavior age at 3 and 1/2 years and his maturational age level below 10 years of age. Ultimately, Dr. Mouille opined Johnson has a mental disease or defect which, when combined with Johnson's intoxication on the night of the shootings, impaired Johnson to the point he could not form specific intent. His written report described Johnson's behavior as a "thoughtless response to the stressors in his environment."
The State's expert, Dr. Vandenberg, disagreed with these conclusions. He hypothesized Johnson had a learning disability and disputed Dr. Mouille's conclusion that Johnson suffered from brain damage. Additionally, he described Dr. Mouille's conclusion regarding Johnson's developmental and maturational age as "absurd" and totally contradictory to Johnson's history and to Dr. Vandenberg's observations of Johnson. Nevertheless, Dr. Vandenberg indicated Johnson is immature for his age; although Johnson was 20 years old at the time of the trial, Dr. Vandenberg rated his functional maturity at lower than age 19. In Dr. Vandenberg's opinion, these factors, combined with his intoxication, compromised Johnson's judgment but did not negate his ability to form intent.
The jury found Johnson guilty of four counts of attempted second-degree murder, severity level 3 person felonies. Johnson had no prior criminal history; thus, he was assigned a criminal history score of I. The applicable grid block for each conviction indicated a prison sentence of 55, 59, or 61 months. See K.S.A. 21-4704. Noting that a random shooting at an apartment complex could result in several deaths, the judge sentenced Johnson to 61 months for each conviction to be served consecutively; however, because of the limitation of K.S.A. 21-4720(b)(4), the total prison sentence was limited to twice the base sentence, i.e., 122 months. Johnson was also ordered to pay court costs and restitution.
Johnson makes a timely appeal. This case was transferred to this court on our own motion because of the issue of first impression raised by the United States Supreme Court's decision in Cunningham, 549 U.S. 270.
State's Experts
As his first issue on appeal, Johnson contends the trial court denied his right to a fair trial by allowing Dr. Vandenberg to testify regarding his mental evaluation after Dr. Vandenberg violated discovery orders entered by the trial court. The State counters that the court correctly allowed Dr. Vandenberg to testify; regardless, any error was harmless because Johnson was not prejudiced.
Factual Background
There is no dispute that Dr. Vandenberg violated a discovery order, which had been agreed upon by the parties. In the order, the trial court required that "[a]ny interviews or conversations with the Defendant by any professional retained by the State to perform a psychological assessment of the Defendant shall be tape recorded." Although Dr. Vandenberg was aware of the order, he recorded only portions of his interview with Johnson. Based on this violation, the defense objected to the State's motion to endorse Dr. Vandenberg and sought to exclude his testimony as a sanction.
At hearings on the defense objections and motions, Dr. Vandenberg testified he believed copyright laws prohibited him from recording standardized test questions because, in doing so, he would be placing those questions into the public domain. In addition, he believed "ethically, I cannot tape-record any kind of an examination without permission of the examinee." While Dr. Vandenberg "thought" he had apprised the prosecutor that he could not record that portion of Johnson's interview, he was "[n]ot entirely sure," and, indeed, the prosecutor advised the court that Dr. Vandenberg did not tell him about the decision to record only portions of the interview.
In ruling on the various motions, the court expressed concern about why Dr. Vandenberg had "the [recorder] off when he indicated [Johnson] made certain substantive questions that would assist the State in showing that [he] knew what was going on." However, the court stated, "it's an impeachment issue" and "also a contempt issue," noting that Dr. Vandenberg "should have gotten the court's permission to not do something when he was ordered to tape, and that was an agreement that the two [parties] have reached."
Specifically addressing the State's motion to endorse, the court commented that a denial of such a motion is not typically ordered for the purpose of issuing a sanction– instead the question of whether to grant a motion to endorse involves "a question of prejudice." The court offered to entertain a recess or "maybe even a continuance of the trial" but, after observing that defense counsel made no such request, found that defense counsel had ample opportunity to examine the materials and prepare for cross-examination and was not prejudiced by the endorsement.
Later, defense counsel filed a motion requesting that the court prohibit the admission of Dr. Vandenberg's testimony or written report at trial as a sanction for violating the court's order. After the defense rested and the State was preparing to call Dr. Vandenberg as a rebuttal witness, the motion was addressed outside the presence of the jury. The trial court denied the motion, noting that defense counsel had been able to question Dr. Vandenberg at a previous suppression hearing and had asked questions regarding the unrecorded portions of the interview. Again, the court reiterated that the defense would be able to impeach the witness regarding the failure to comply with the court order.
At trial, defense counsel vigorously cross-examined Dr. Vandenberg regarding his conclusions, asking him about specific questions on the standardized tests. In addition, defense counsel thoroughly cross-examined Dr. Vandenberg about his decision to shut off the tape recorder. As the trial court predicted, these questions highlighted Dr. Vandenberg's potential bias toward the State.
After the trial, the court found Dr. Vandenberg to be in indirect contempt of court. In doing so, the court made additional findings that explained its view of Dr. Vandenberg's conduct, noting Dr. Vandenberg "conducted the evaluation and turned off the tape recorder, an intentional act, during a small part of the evaluation. This was a clear violation of the court's order." Nevertheless, the court did not believe Dr. Vandenberg's motives were "sinister." But the court felt the matter was serious and ordered Dr. Vandenberg (1) to pay the attorney fees associated with the contempt proceeding and (2) to seek direction or decline cases in the future if he does not believe he can comply with a court order.
On appeal, Johnson argues the trial court should have done more and should have excluded Dr. Vandenberg's testimony because, although Johnson was present during the psychiatric examination, defense counsel had no independent means of determining what occurred during the unrecorded portions of the examination and was forced to rely on Dr. Vandenberg's own recollection.
Was it error to allow Dr. Vandenberg to testify?
The parties disagree on the appropriate standard for appellate review of the trial court's decision to allow Dr. Vandenberg's testimony. The State argues we should apply an abuse of discretion standard; the defense urges a de novo standard.
Generally, the admission of expert testimony lies within the sound discretion of the trial court, and its decision will not be overturned absent an abuse of such discretion. State v. Corbett, 281 Kan. 294, 317, 130 P.3d 1179 (2006); State v. Holmes, 278 Kan. 603, 623, 102 P.3d 406 (2004); State v. Brice, 276 Kan. 758, 775, 80 P.3d 1113 (2003). Here, no question is raised regarding the typical issues surrounding the admission of expert testimony; there is no question regarding Dr. Vandenberg's qualifications, the relevancy of his opinion, or Dr. Vandenberg's ability to assist the jury in understanding technical facts or material evidence. See K.S.A. 60-456(b), (d); State v. Struzik, 269 Kan. 95, Syl. ¶ 3, 5 P.3d 502 (2000). Rather, the sole question is whether the trial court should have excluded the testimony as a sanction for the discovery order violations.
K.S.A. 22-3212(g) authorizes a broad array of sanctions for violations of discovery orders in criminal cases, including permitting the discovery or inspection of materials not previously disclosed, granting a continuance, prohibiting the party from introducing into evidence the material not disclosed, or entering "such other order as [the court] deems just under the circumstances." By granting the option to impose sanctions the trial court deems "just," the provision grants discretion to determine the appropriate sanction. Consequently, a trial court's denial of a motion seeking to exclude the testimony of a witness who violated a discovery order in a criminal case is reviewed under an abuse of discretion standard if due process rights are not implicated by the violation. See Pierce v. Underwood, 487 U.S. 552, 559, 101 L. Ed. 2d 490, 108 S. Ct. 2541(1988) ("language and structure of the governing statute" may determine standard of review).
Johnson argues, however, that we should apply a de novo standard because his due process rights are implicated. Yet Johnson fails to cite any authority to support his contention, and we cannot find a basis for such a conclusion. A criminal defendant does not have a due process right to have expert witnesses record interviews. It was entirely within the trial court's discretion to order the recording of the interview or to allow the interview to be conducted without a recording. Nor is there a due process right to have testimony excluded when the witness or a party violates a discovery order because K.S.A. 22-3212(g) grants discretion to the trial court to determine the "just" sanction. Such a sanction could take many forms other than suppression of the evidence. Consequently, a due process interest did not arise. See Robinson, 281 Kan. at 547 ("A due process violation can be established only if a claimant is able to show that he or she was denied a specific procedural protection to which he or she was entitled.").
Additionally, although an accused has a due process right to a fair trial, due process does not guarantee a perfect trial. See State v. Lumley, 266 Kan. 939, 962, 976 P.2d 486 (1999); United States v. Stevens, 612 F.2d 1226, 1229-30 (10th Cir. 1979). The lack of a recording of a small portion of the interview, even if a recording was ordered by the court, did not deprive Johnson of a fair trial. Johnson was left in the same situation as many criminal defendants where interviews are not recorded, except he was able to impeach Dr. Vandenberg regarding his failure to follow the court order. Moreover, Johnson was able to present his defense.
Therefore, we conclude that if a witness violates a discovery order in a manner that does not implicate due process, an abuse of discretion standard governs appellate review of a trial court's decision to admit the witness' testimony rather than to exclude the testimony as a sanction permitted by K.S.A. 22-3212(g). Under the facts of this case, we reject Johnson's argument that discretion was abused by denying the motion to exclude Dr. Vandenberg's testimony. While Dr. Vandenberg did not fully comply with the court order, the record shows that defense counsel was able to thoroughly cross-examine him regarding his professional opinion of Johnson's mental capacity and his methods for evaluating Johnson. Also, the record reflects that Dr. Vandenberg relied largely on data provided by the defense expert, Dr. Mouille, in rendering his opinion. Dr. Vandenberg testified that he repeated tests only to the extent of double checking the accuracy of Dr. Mouille's conclusions, and the trial court found this was only a small portion of the interview. Moreover, the violation of the order potentially diminished the weight of Dr. Vandenberg's expert testimony. The trial court struck an appropriate balance by ordering sanctions but allowing the testimony.
Thus, the trial court did not abuse its discretion in admitting Dr. Vandenberg's expert opinion testimony regarding Johnson's mental capacity.
Confession Johnson filed three pretrial motions to suppress his statements to officers, all of which were denied. On appeal, Johnson reiterates that his state of intoxication, combined with his limited intellectual capacity, rendered his statements to officers involuntary. More specifically, Johnson contends that he did not understand his right to remain silent.
Factual Background
Drs. Mouille and Vandenberg were also asked to evaluate whether Johnson was able to understand his right to remain silent. At hearings on the various motions to suppress, the trial court heard testimony regarding their contradictory opinions. Dr. Mouille opined that Johnson understood his right to counsel but believed he was required to talk to the detectives. Dr. Vandenberg, on the other hand, concluded that Johnson had the capacity to understand the Miranda warnings. Dr. Vandenberg's opinion was buttressed by the fact that Johnson initially refused to participate in the psychiatric interview until Johnson had spoken to his attorney. This postponed Dr. Vandenberg's interview until the following day.
The court also considered the preliminary hearing testimony of Detective Burket, one of two detectives who interviewed Johnson. Detective Burket indicated that after allowing Johnson to sleep overnight in the local jail because of concern about his being inebriated, he and Detective Mike Schneider interviewed Johnson the next morning at about 10:45 a.m. Because Johnson had just woken up, the detectives ordered a tray of food for him. The detectives were dressed in plain clothes, and neither had a weapon.
The detectives told Johnson they had talked to "a lot of witnesses, including people that were in his vehicle with him" and knew he fired the gun. They indicated they had one side of the story and wanted to hear his side. Then, they asked if he would be willing to talk to them, and Johnson agreed. Next, Johnson was read his rights per Miranda and waived them. Before Johnson signed a waiver, the detectives explained that he did not have to do so if he did not want to. Johnson also agreed to give a written statement.
Detective Burket testified that Johnson spoke appropriately, made sense, and was cooperative and polite. The detective denied having any concerns about Johnson remaining under the influence of alcohol or some other substance. In addition, Detective Burket denied making any threats or promises to Johnson.
Johnson told the detectives about the chronology of events on the night of the shooting and also explained he shot the gun to protect one of his companions and to scare the individuals on the balcony in an attempt to let them know not to "mess" with him.
At the conclusion of the oral interview, the detectives asked Johnson for his written statement. They inquired about his level of education, to which Johnson replied that he did not graduate from high school but passed a "life skills course." Detective Burket once again read the Miranda rights, which were listed on the form, and explained to Johnson that "it was the same as before only for a written statement." Johnson signed the form, and the detectives stepped out of the room while he completed his statement for 15 to 20 minutes.
Then, around 1:30 p.m., after Johnson had completed his written statement, a tape recorder was delivered. Detective Burket asked Johnson if he would submit to a recorded interview. The detective started the recorder, but Johnson said at the very beginning of the recorded statement that he wanted an attorney. Therefore, the detective immediately terminated the interview.
Based upon the evidence, the trial court found that Johnson was of low average intelligence but was "certainly quite a functioning individual" and "was able to make decisions." Although the court acknowledged Dr. Mouille's testimony regarding Johnson's understanding his right to have an attorney versus his right to remain silent, the court failed to see the distinction the defense tried to draw between these two concepts. The judge stated: "I think there is some dovetailing involved in these particular matters." The court observed that after a period of time during the interview, Johnson told the detectives he "did not want to talk to [them] anymore. He asked for an attorney."
Looking at the totality of the circumstances and testimony, the court found the State showed by a preponderance of the evidence that Johnson's "statements made to the police officers were voluntary, were not in violation of Miranda."
Was it error to admit Johnson's statements?
In reviewing a trial court's decision regarding suppression, this court reviews the factual underpinnings of the decision by a substantial competent evidence standard and the ultimate legal conclusion by a de novo standard, applying independent judgment. This court does not reweigh evidence, pass on the credibility of witnesses, or resolve conflicts in the evidence. State v. Harris, 284 Kan. 560, Syl. ¶ 9, 162 P.3d 28 (2007); State v. Ackward, 281 Kan. 2, Syl. ¶ 1, 128 P.3d 382 (2006).
It is well established that voluntariness of a confession must be determined under the totality of the circumstances. The State has the burden of proving that a confession is admissible, and the required proof is by a preponderance of the evidence. The essential inquiry is whether the statement was the product of the accused's free and independent will. State v. Brown, 285 Kan. 261, 272, 173 P.3d 612 (2007); State v. Gonzalez, 282 Kan. 73, 103, 145 P.3d 18 (2006). Numerous factors are to be considered when determining if a statement was voluntary, which this court has consolidated into the following nonexclusive list based on previous Kansas case law:
"(1) the accused's mental condition; (2) the manner and duration of the interrogation; (3) the ability of the accused to communicate on request with the outside world; (4) the accused's age, intellect, and background; (5) the fairness of the officers in conducting the interrogation; and (6) the accused's fluency with the English language." State v. Walker, 283 Kan. 587, 596-97, 153 P.3d 1257 (2007).
In this case, the defense focuses upon the accused's mental condition and intellect. No other factor weighs against a conclusion that Johnson's waiver of rights was involuntary, and the absence of other factors is an important consideration. This point was emphasized in State v. Swanigan, 279 Kan. 18, 30-39, 106 P.3d 39 (2005), a case in which the defendant had an I.Q. of 76. In that case the defendant relied upon several factors, causing this court to note:
"Although any one of these factors which Swanigan asserts–his low intellect and susceptibility to being overcome by anxiety, the officers' repeated use of false information, and their threats and promises–may not be sufficient to show coercion, the combination of all of them in this case leads us to conclude as a matter of law that Swanigan's October 31 statement was not the result of his free will, but was involuntary." 279 Kan at 39.
In contrast, when low intellect is the only factor, in several cases this court has concluded the statement is knowing and voluntary. For example, in State v. Thompson, 221 Kan. 165, 558 P.2d 1079 (1976), the defendant alleged that he was incapable of voluntarily and intelligently waiving his right to remain silent due to the fact that he had an I.Q. of 68. In affirming the trial court's determination that the statement was freely, voluntarily, and intelligently given, the Thompson court stated that "[t]he mental deficiencies of the defendant may be an important factor in determining whether or not a confession was voluntarily given. That fact alone, however, is not conclusive evidence on the issue." 221 Kan. at 170; see also Colorado v. Connelly, 479 U.S. 157, 163-65, 93 L. Ed. 2d 473, 107 S. Ct. 515 (1986) (low intellect not basis for finding statement involuntary if no coercion); State v. Mays, 277 Kan. 359, 374-76, 85 P.3d 1208 (2004) (verbal I.Q. of 77 was only one factor); State v. Lane, 262 Kan. 373, 386, 940 P.2d 422 (1997) (I.Q. of 77 was only one factor); see generally Annot., 8 A.L.R.4th 16.
In other words, Johnson's low intelligence does not preclude a finding that Johnson knowingly and voluntarily waived his Miranda rights. The waiver may be knowing, as defined by constitutional requirements, if the circumstances indicate Johnson understood his constitutional rights and the consequences of asserting or waiving those rights. Further, Johnson's waiver of rights may be voluntary if law enforcement officers did not exploit his low intelligence or otherwise coer