Aaron Hernandez has been in jail for four months as he faces murder chargers for the death of Odin Lloyd. Now, the grand jury that indicted the former NFL star is investigating him for gun trafficking.

According to CNN, Hernandez is suspected of being involved in the illegal transportation of weapons across state lines. The report states that authorities found an assault rifle in a car in Massachusetts that is connected to the investigation.

As the grand jury looks into Hernandez’s potential involvement in gun trafficking, one of the ex-tight end’s college teammates has been hit with a subpoena. Miami Dolphins center Mike Pouncey was served on Sunday after the team’s game in New England, according to Sports Illustrated. Pouncey was met by Massachusetts State Police as he headed towards the team bus.

Pouncey isn’t expected to face any charges in the case, but to just speak with the grand jury. He is good friends with Hernandez, who he played with at the University of Florida. Pouncey and his brother Maurkice, who plays for the Pittsburgh Steelers, were photographed wearing hats that read “Free Hernandez” in July.

The Dolphins have refused to comment on the situation, as have the Steelers. On Sunday, Pittsburgh will be in New England to play the Patriots.

While Pouncey may not face chargers, several associates of Hernandez have been indicted in relation to the murder of Lloyd. Hernandez’s fiancée has been charged with perjury, and his cousin has pleaded not guilty to criminal contempt and being an accessory to murder after the fact. Hernandez’s friends Ernest Wallace and Carlos Ortiz have been charged with being accessories to murder, after they were allegedly with Hernandez on the night that Lloyd died.

Hernandez was hit with five weapons charges when he was initially indicted. They stem from the bullets police found when raiding the ex-football player’s home.