Nigerian email scams and hoaxes have been bouncing around the Internet for years. The email scam basically consists of a scenario where the con artist states that he has a large sum of money that for various reasons, he needs to hide in your bank account. In return you will get a large sum of cash.
The email scam has been modified to involve Switzerland and Holocaust victims. They claim to be a victim and need you to get the money they rightfully deserve. They then send you a bogus check which you cash, keep your sum and then send them the remainder. The check then bounces a couple of weeks AFTER you have deposited into the bank. (Just because a bank makes the funds available, does not always mean that the money has cleared).
Long story short, don’t accept checks or send cash to anyone that you have met on the Internet. More likely than not it is an email scam or Internet hoax.