Potentially incriminating evidence mounts as the case against former New England Patriots tight-end Aaron Hernandez moves forward.
CNN's Susan Candiotti reports more questions arise about a man who may be playing a key role in the investigation.
Not much is known about Carlos Ortiz, but what we know is intriguing.
The District Attorney identifies Ortiz as one of two men in a car with accused murderer Aaron Hernandez the night Odin Llyod was gunned down execution style.
"There was a conversation that occurred in the car where he gets into argument with the victim."
How might investigators know about what went on in the car?
A law enforcement source tells CNN Ortiz is cooperating with authorities, but won't go further.
"If Ortiz is a cooperating witness that's a big, big break for prosecutors."
Ortiz, for now, faces only an illegal weapons charge for allegedly telling police he was carrying a gun the day Lloyd was murdered.
Ortiz pleaded not guilty to the gun charge, his attorney declined comment to CNN.
According to a search warrant, Ortiz told police the day after Lloyd's murder, he and Hernandez drove to a two bedroom apartment.
Police call it a flop house. Documents show the football player leased it almost 20 miles from his luxury home, no explanation why.
A neighbor says she barely saw the famous renter.
"No suspicious activity, no girls, nothing other than just typical guy stuff. A little bit loud, a little bit of cigarette smoke, a little bit of maybe pot, but nothing you wouldn't expect from a bunch of guys."
Hernandez has pleaded not guilty. Lloyd's murder investigation is now moving to the grand jury stage.
CNN has learned a grand jury already is calling witnesses, some scheduled to appear within the next two weeks.