Who’s at fault?

I posted in r/caraccidents, but would like the opinion of more peeps.

My sister got into a very minor car accident when she was tuning right at a red light. I was trying to convince her it was her fault, but after googling the law in Texas it’s legal to turn right into your own lane as long as it’s been deemed safe and there are no pedestrians. Well as soon as she turned a black truck got into her lane with no blinker and no indication he would get into her lane.

Who’s at fault? Does not using the blinker have anything to do in this situation?