( CNN ) -- A witness sources have described as Aaron Hernandez 's `` muscle man '' says he was with the ex-New England Patriot the night of a 2012 Boston double homicide that police say may be linked to Hernandez , said a law enforcement source with knowledge of the investigation . The witness , Alexander Bradley , has filed a civil lawsuit accusing Hernandez of shooting him in the face during an argument after they left a Florida strip club in February . Bradley lost sight in one eye because of the incident , according to the lawsuit . In what could be a crucial account for the prosecution , Bradley is telling investigators that he was at Boston 's Cure nightclub -- with Hernandez -- on July 12 , 2012 , before Daniel Abreu , 29 , and Safiro Furtado , 28 , were fatally shot in their car , the law enforcement source said . Bradley and Hernandez were also captured on the nightclub 's security camera , the source said . Bradley has testified before a grand jury in Boston after being arrested last week because he failed to show up for a court proceeding about a grand jury subpoena . A Boston grand jury has been hearing evidence allegedly linking Hernandez to the double homicide , sources have told CNN . Among the evidence is a .35 caliber handgun sources describe as the murder weapon in the double homicide . In addition , a silver SUV driven by Hernandez was discovered covered with dust in his uncle 's garage , law enforcement sources say . Law enforcement sources say the SUV is believed to be linked to the deaths . Hernandez 's lawyers have not commented about the investigation . The SUV was found as investigators searched the uncle 's home in Bristol , Connecticut , in connection with another shooting death , that of Odin Lloyd . Hernandez is charged with Lloyd 's murder and has pleaded not guilty . He appeared in court Wednesday for a pretrial hearing in that case . Prosecutors say Hernandez orchestrated Lloyd 's June 17 execution-style shooting . Authorities have said that Hernandez , Wallace , and a third man , Carlos Ortiz , picked Lloyd up from his Boston apartment in a rental car shortly before his death . Surveillance cameras then captured the rental car leaving the crime scene and Hernandez carrying a gun as he returned to his home minutes later . He was with two other people . Lloyd was not among them .
Source : A witness says he was with Aaron Hernandez the night of Boston double homicide . A grand jury is hearing evidence in the July 2012 shootings , a source says . Comment: Ex-New England Patriot Hernandez has pleaded not guilty in a separate slaying .