SHIRLEY, MASS. (WHDH) - The Massachusetts prison where Aaron Hernandez was found dead last week is on lock down as investigators scour the maximum security facility for evidence related to the ex-New England Patriots star’s death.

Officials at the Souza-Baranowski Correctional Center in Shirley, where authorities say Hernandez hanged himself with a bed sheet, said the prison has been locked down to accommodate a “special operations search.” The Massachusetts State Police are leading the effort.

RELATED: Lawyers want Aaron Hernandez’s murder conviction dismissed

Sources told 7News that officers were searching cells for contraband in connection with Hernandez’s death, including synthetic marijuana, which can be smuggled by dipping paper into the liquid drug and mailing it in an envelope.

While crews worked at the prison, attorneys representing Hernandez filed a motion, formally asked that his first-degree murder conviction be dismissed in Massachusetts now that he has died.

Courts in Massachusetts have held that when a defendant dies before having an appeal heard, the conviction is vacated.

In a rare movie, New Bedford District Court judge Thomas McGuire released audio transcripts from a sidebar discussion between Hernandez’s lawyers and Secretary of Public Safety Daniel Bennett.

“It’s going to be in lockdown. I actually don’t want to say how long it going to be in lockdown. But it’s in lockdown and one of the reasons is because of the issues with Mr. Hernandez and things that have happened with Mr. Hernandez,” Bennett was heard saying.

Come to find out, those issues centered around Bennett’s concern about the release of the suicide notes that were found in Hernandez’s cell.

“I don’t even know, I have never seen those letters. I have a police report with references to the three letters and a reference to how he’s going to be. Essential don’t cry for him. He’s going to be happy,” Bennett said.

RELATED: Aaron Hernandez’s suicide notes released to family on judge’s order

Correctional officials are not allowing guests inside the prison walls as the search continues. It’s not clear what investigators found or when the lockdown will be lifted.

On Monday, three suicide notes that were found in Hernandez’s cell near a Bible where released to his family, per order of a New Bedford District Court judge.

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