The day after John Zera's body was found, Daniel Acker was found standing over the crime scene in Whitnall Park. His alibi for the day of John's death was shaky, but police dismissed him. Acker would strike up a correspondence with the Zera family and start his own investigation into the case, pointing the finger at a mental patient at the facility where he worked.

For more information on the true crime series Unsolved: A murder mystery podcast, visit http://usatoday.com/unsolved.

For more reporting on cold cases, unsolved cases and true crime detectives, as well as additional true crime stories and investigative journalism visit witness.usatoday.com. Crime reporter and investigative reporter Gina Barton is also host of Untested: A true crime podcast, in which Annie Harrison joins the rank of true crime detectives as she solves the cold case of a possible serial rapist. Subscribe to Untested: A true crime podcast at https://art19.com/shows/untested

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