Former New England Patriots tight end Aaron Hernandez is being investigated by Bristol County jail officials for allegedly passing a handwritten note to another inmate.  The note, hidden in a book, was sent to the inmate who tried to steal Hernandez's ID card, TMZ reports.

Hernandez reportedly contacted the inmate who attempted to abscond with his jail ID card by giving the inmate a copy of the book, "Bad Boy Brawly Brown," which contained the handwritten note.  The note, scrawled on two pages inside the book, began with: "I heard you are the one that tried to steal my ID!  That's crazy lol!"

The note then goes on with Hernandez saying he's innocent, anxious to prove it in court and confident he will one day return to the NFL.  The handwriting appears to match two of Hernandez's previous letters, according to TMZ.

Given that inmates are prohibited passing notes to each other, Hernandez could face consequences if the investigation reveals he committed the infraction.  Jail officials were apparently tipped off about the note from the inmate who received it.

The case against Hernandez outside of jail, meanwhile, continues to grow.  Investigators reportedly believe the ex-NFL star may have been involved in a "large-scale, multi-state gun running operation," based on a subpoena issued to Miami Dolphins center Mike Pouncey, a friend and former college teammate of Hernandez's.

"The source indicated that police are focusing in on Hernandez's potential involvement in interstate gun trafficking, which is being investigated by several agencies in multiple states - at least Massachusetts, New York and Florida," Sports Illustrated wrote on Sunday.

Hernandez, 23, is being held without bail while he awaits trial for first-degree murder and five gun-related charges in the murder of Odin Lloyd.  Hernandez pleaded not guilty and faces life in prison if convicted.  

*This article has been updated (10/30/13).