I'm two eps behind rt now but my bet is it's neither Naz (although the guesses of him committing a crime in prison make sense) nor Duane Reid (sp?) since tbh he would be too obvious.

But that blacked-out limo or towncar at the gas station, with the driver who iirc had an American flag pin and was eyeing the girl in the cab, and then may have followed them, was most probably connected to the reason she was afraid in the first place, and then responsible for her death.