I have found stolen photos, how can I help this person?

Scammers can take anyone's picture off Facebook, Google, Instagram, porn sites, model agency websites, webcam sites, blogs or anywhere else they are posted. Your chance of finding the real person are slim. There are now 1 billion Facebook accounts so it would be rare if anyone recognised the person
Just report the scammer's profile to the site where you met or if you lost money, file a police report

There are zillions of instances of this all over the internet. You cannot prove that the pics are stolen from someone else, and, as it is email, there is little you can do as an end user. Learn to be more savvy about emails and block those who try to scam you. Almost anything offering free cash, friendship or goods is going to be a scam. Stick to opening mails only from well known friends and family and spam the rest. It is possible, but not practical, to find other instances of these pictures as they occur online, but trying to track down the actual owner is a nigh on impossible task. Just protect yourself, because if we all do that, scammers can do much less harm to all.

Nev & Max

Report them to the place where you found then and get them taken down is about all you can do

The pictures scammers tend to be images they've grabbed off Google. They'll be easy enough to get.
Reporting to the person that owns the pictures won't stop a scammer from using them, in fact, how would you feel if your image was being used to scam people and you were powerless to stop them? I'd feel terrible.
My personal opinion is that its best just to delete them.