Got mugged on the train with a gun

A couple years ago I was on the train at night. Two men jumped me with a gun and a knife. Fortunately a police officer was in the next car and heard the altercation. He handcuffed them, took my statement, and left with them at the next stop.

He never followed up and I never found out what happened to them. Apparently there's no records in the police database either. Did I do something wrong? Idk what normally happens in cases like these.