Is it obligatory to inform the police about a person we have confirmed burned a university professor's car, after we had previously cooperated with the police in the investigation and he was not uncovered?

Testimony is a grave matter in Islam, which is why Islamic law has warned against false witness and deemed it among the gravest of major sins. It has also urged giving truthful testimony and mandated that the witness verify and ascertain the facts. Therefore, if you are certain that the person your friend mentioned is indeed the one who burned the car, you must inform the police and testify, especially if no one else knows about it, so that the right of the oppressed person is not lost. However, if you are not certain, it is not permissible for you to implicate an innocent person based merely on suspicion or doubt.