I was having this conversation not long ago with my son of 19 due to something similar on the telly (he has an 18-year-old girlfriend) and he was saying he was not at all interested in girls of 14, 15, 16 - phew! - cos he didn't have anything in common with them - too young, too immature, too "silly", etc.
(I'm a single mum so have always made sure we can talk about anything and everything, better the devil you know than the devil you don't IYSWIM).
I'm not saying your daughter is immature OP, but I would be worried, especially knowing his background. (damaged).
The best thing you can do with your daughter is to keep the lines of communication open with her and let her know that whatever the circumstances, you'll be there for her.
I wouldn't report him to the police, (you will alienate them both), better to invite him over, welcome him into the house (as a friend of your daughter's) and know what is going on and then you can check out his motives...
And like another post says, make her aware that she knows her education is nr. 1 at the moment.
All the best!