Elderly Parent Scammed

r/

Location: California

My dad is in his 70s and going through cancer treatment so is a little spacey at the moment.

He put his truck up for private sale and two men came to check it out and test drive.

During the test drive a bunch of smoke came out from the hood indicating significant engine damage.

They offered him 25% of the asking price, and not being in his right state of mind he accepted and signed over the pink slip.

After the transaction my parents checked the ring camera footage and saw one of the guys pour something (oil?) on the engine before the test drive.

He got scammed and a police report was filed, but I’m wondering if there is any legal action they can take to rectify the situation.

Thank you in advance.