A cocktail of drugs including antipsychotic medication, pain medication and muscle relaxants was found in 8-year-old Leiby Kletzky's system, a medical examiner said Wednesday. 

Levi Aron, a 35-year-old maintenance supply worker, was arrested for the murder and dismemberment of the Orthodox Jewish boy in the predominantly Jewish neighborhood of Borough Park July 13. Aron implicated himself in the murder and told police that he had abducted the boy and decided to kill him when he heard that police were frantically searching for him. 

When I saw the fliers, I panicked and was afraid, Aron said, according to police.

Aron told police where the boy's remains were, in his refrigerator and a plastic bag inside of a red suitcase in a trash bin. Aron cut up the small boy with three bloody carving knives using a carving board. He also confessed to suffocating the boy with a towel, police and prosecutors said.

CBS Station WCBS said that the home will remain under police guard while a grand jury in Brooklyn arranges a murder indictment. 

Prosecutors maintain that Leiby Kletzky asked Aron for directions when he became lost while walking home from camp.

Aron pleaded not guilty Thursday. 

Investigators are wondering if Aron has had this type of disturbing contact with children in the past, said the prosecutor. 

Aron, who told defense attorney Pierre Bazile that he hears voices, is under suicide watch. The defense said that Aron giggles sporadically despite the serious nature of the charges and that he may not understand the charges against him.