I'm sure this JN character is going to try to find a way to pin this on someone else. I think at the end it will be quite simple: he was swindling them, and they found out and threatened to report him to LE/the feds. This guy was not going to go back to prison, especially after having served time for "not doing anything wrong". Pretty tight window if everything was fine at 11, but with a gun, it takes seconds to shoot two people dead. And I'm sure everyone out there is carrying. Everything could have been fine at 11 and they could've been dead by 11:15.