Damien was only a teenager when his father died in a car crash. He grieved and mourned for him, but he didn't question the incident because he didn't have any reason to. It wasn't until Amelia told him her doubts that he started questioning what he knew.
The fact that the police officer disappeared soon after was very suspicious. It was long overdue that he got to the bottom of the truth. Whether it really was an accident or not.
Detective Donovan gave him an address that was quite a distance from Harbor City. Damien wanted to handle it personally and it wasn't the detective's job to do his bidding, so he thanked him and kept their conversation brief, making a mental note to send him a gift later.
