What will happen if I make a citation even if I was not there to witness it?

My mother was backing out of a private parking lot. She had stop and put the truck in drive, at that moment a women backed into her. Before the women got out of her van she had already called the local police department. Before the police arrived the women moved her van. My mother waited till the police officer had her move her truck. There were witnesses to the accident and the officer did not speak to them. He then spoke to my mother for about five minutes and asked my mother " were you backing up" she then replied to the officer that she had backed up, came to a stop, and had put the truck in drive and that was when she got hit. The officer then talked to the other woman (which they know personally because she is the manager a local gas station where the Police Department gets there gas for their police cars). For about 30 minutes, the officer then came back and told my mother “that my mothers and the other women's stories were about the same. But I have to write someone a citation and that since I was not there to witness it; I hope I am making the right decision". He didn't ask the woman that I was with my mother, or the employees of the pharmacy or the other witnesses what had happened. Can you give me any advice to what to do?