Both were not jewish.
So basically there isn't any proof that he targeted those 2... He could have tried all your contacts as Dan said, and the Jewish ones wouldn't have known as etech0 said.
How he seemingly got your contacts is a mystery. Though, if he traced the calls, that's how he could have gotten the numbers, just basing it off who you called, and hoping you were in their contacts.
Hopefully it'll pass. Good Luck!