I was thinking that the police were delicately hinting here that maybe the would-be grieving widow did something to cause the crash-maybe not. But the fact that she was so eager to watch her beloved lifemate (/s )starve slowly to death has to raise at least fleeting suspicion...
She told them that she was attempting to jump out of the vehicle, and he lost control when he tried to prevent her from jumping. For the police to say they haven’t determined what caused him to lose control of the car, suggests to me that they don’t buy her version. I suppose they’ll know more, when and if Jesse begins communicating clearly, if he can remember the event.