Yahoo Personals - predators?

Ok, so my friend had been talking with this guy on the personals for a month and he would always dodge personal questions she was asking. One day, he asked if he could call her. She said yes, gave him her number and he blocked his number when he called her. That was weird. Then, later on, she finally got his number from him but when she called it, he hung up. She asked why and he made up some lame excuse. Anyway, her mom ran a trace on his phone number. It was listed under someone else's name. We googled THAT name and found a different photo of a different guy. So, obviously he is using another guy's pic to run his Yahoo personal ad and even another guy's name. He's a weird freak too. So what do we do now? Do we tell the Yahoo people or what?