holding that jury returning verdict 45 minutes after informed would be sequestered in hotel was not coerced into verdict

holding in People v. Gacho, 122 Ill.2d 221, 119 Ill.Dec. 287, 522 N.E.2d 1146, cert. denied, 488 U.S. 910, 109 S.Ct. 264, 102 L.Ed.2d 252 requiring new instruction in multiple murders involving mitigating evidence in capital cases was prospective only; Griffith, not applicable

rejecting defendant's argument that his borderline mental retardation rendered his confession involuntary in the absence of proof of police overreaching