Car accident claim days later
On Saturday, 3 days ago, my sister was backing out of a parking spot in our apartment complex and rear ended a truck parked illegally in the fire lane behind her. There is a pretty sizable dent in his car. Neither thought to call the police and make a claim. The truck that was hit claims to have insurance, but refuses to give any information because he doesn't want his premium to go up next year and will only work through my sisters insurance.
My question is, because there was no police report, no pictures taken until 3 days later, and one party refuses to share their information, and was parked illegally, can my sister really be held responsible and made to pay for the damages through her insurance?