Who was the person who turned in Anne Frank's family in?

Well, nobody's sure. Anne thought it was one of burglars who robbed Mr. Frank's offices. It could have been too. The burglar was robbing them at night, when the annexe became alive and filled with noise. If I heard that, I would have thought that those people where having a party or they were hiding Jews. But I wouldn't have turned the Franks in.