Christopher Diaz, a prisoner at DeKalb County jail, told prosecutors on Wednesday that he overheard Jack McCullough, 72, tell another inmate how he killed Maria Ridulph, 7. Diaz said the conversation included details about how he strangled her with a wire, according to a Daily Chronicle article.

McCullough is on trial for allegedly kidnapping and murder Ridulph on Dec. 3, 1957.

The inmate who allegedly had the discussion with McCullough is scheduled to testify as a John Doe witness. Diaz said prosecutors have not offered him anything in return for his testimony.

Krista Latham, a molecular and forensic anthropologist at the University of Indianapolis, said she observed Ridulph’s remains on July 27, 2011. She said three deep cuts to the bones of Ridulph’s throat and chest looked to have been made by a knife.