(CNN) Investigators officially ruled Aaron Hernandez's death a suicide and released new details about the circumstances of his hanging on Thursday.

In particular, investigators found three handwritten notes next to a Bible in the prison cell. It was not immediately clear what those notes said.

That information comes from a joint statement from Worcester County District Attorney Joseph Early Jr., Massachusetts State Police Superintendent Col. Richard McKeon, and Secretary of Public Safety Daniel Bennett.

Hernandez's died early Wednesday morning after he hanged himself by a bedsheet in his prison cell , the Massachusetts Department of Correction said. The former tight end for the New England Patriots had been serving a life sentence without parole after being convicted in the June 2013 murder of Odin Lloyd.

Hernandez was found dead with the words "John 3:16" written on his forehead, according to a law enforcement source directly involved in the investigation into the former NFL star's death.

The notation is believed to refer to the words in the Bible from John 3:16: "For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life."

Law enforcement personnel told CNN's Deborah Feyerick that inmates often use this verse.

According to the joint statement, Hernandez was locked in his cell about 8 p.m. on Tuesday night, and no one entered the cell until he was found by a correction officer at 3:03 a.m. He was taken to a hospital and pronounced dead about an hour later.

Cardboard had been jammed into the door tracks of his single-inmate cell to impede entry, according to the statement. There were no signs of a struggle and he was alone at the time.

Hernandez's death came just five days after his acquittal in the 2012 slayings of two men outside a Boston nightclub in a separate case.

This article has been updated to better characterize details about the manner in which the Bible verse was written. CNN continues to gather reporting to clarify the information.