BROOKLYN - Authorities investigating the death and dismemberment of a Brooklyn boy say there are still many unanswered questions surrounding the case, even though the suspect has been forthcoming with details.

Police say 35-year-old Levi Aron confessed to luring Leiby Kletzky to his home on Monday, and then smothering him and chopping him up when he learned that a search was under way for the missing child. Aron pleaded not guilty today to murder and kidnapping charges. His lawyer told the court his client hears voices.

NYPD Commissioner Ray Kelly says the events of the case still don't add up. Police are trying to determine what set off the chain of events that caused Aron to allegedly kill Kletzky.

Aron is expected to undergo a psychiatric evaluation.Massive manhunt under way for missing 8-year-old boy Police find missing BK boy's remains, arrest suspect VIDEO: Full press conference about Leibby Kletzky case Thousands attend funeral for slain BK boy