They were put on trial in 1921. They were convicted even though evidence was clear that they had not committed the crime. This evidence involved ballistics tests and several witnesses who claimed Sacco had been in Boston and Vanzetti in Plymouth on the day of the robbery. The two men were carrying weapons when they were arrested. To explain this, Sacco and Vanzetti had to explain their anarchist beliefs in court. It is believed that this may have prejudiced the jury (influenced their decision).