Police served Miami Dolphins center Mike Pouncey with a subpoena on Sunday in connection with the Aaron Hernandez case.  The grand jury subpoena suggests authorities have focused their investigation on to whether Hernandez was involved in interstate gun trafficking, Sports Illustrated reports.

Pouncey received the subpoena shortly after Miami's 27-17 loss at Gillette Stadium.  Two Massachusetts State Police officials dressed in suits approached Pouncey between the Dolphins' locker room and team bus and handed him a piece of paper. 

"It's about a grand jury investigation," one of the officials was overheard telling Pouncey, according to Sports Illustrated.

Dolphins officials, like Pouncey, were caught by surprise; Patriots owner Robert Kraft had not been made aware that Pouncey would be issued a subpoena, according to a team official.

Sports Illustrated was told by a source that the subpoena was issued in connection with the ongoing Hernandez investigation.

"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. 

"The extent of Pouncey's involvement is undetermined, but police are focusing on multiple transactions that involve him and Hernandez."

Pouncey and his twin brother, Steelers center Maurkice, were close friends and former teammates at the University of Florida with Hernandez.  Although never charged, Mike, Maurkice and Hernandez's names appeared in a 2007 police report regarding an unsolved shooting in Florida.

The Pouncey brothers were pictured over the summer wearing "Free Hernandez" hats.

Although the subpoena indicates authorities believe Hernandez may have been involved in a "large-scale, multi-state gun running operation," Hernandez hasn't been charged for any weapon trafficking crimes.

Hernandez also is being investigated for an unsolved 2012 double homicide in Boston.

The ex-NFL star pleaded not guilty to the first-degree murder of Odin Lloyd and five gun-related charges.  He's currently in jail and being held without bail while awaiting trial.