How do you determine who is at fault in a police accident report when cars are described as unit#1 and unit#2?

Question

Was hit head on by a car that crossed the double yellow line premature to turn into a neighborhood.

Answer 1

If a police officer, marks any vehicle as unit # 1 in any car accident, it means that it is safe it had no active part in the accident. However the car marked as the unit #2 is the one that is guilty of collision, and responsible for the accident.