A Pennsylvania AO-90 Subpoena to Testify at a Deposition in a Criminal Case is a document issued by a court or law enforcement agency to require someone to appear at a deposition in a criminal case. The subpoena will usually require the recipient to give sworn testimony under oath and may also require them to bring certain documents or records. There are two types of Pennsylvania AO-90 Subpoena to Testify at a Deposition in a Criminal Case: witness subpoenas and party subpoenas. A witness subpoena is issued to a person who is not a party to the criminal case, such as a witness, expert, or third-party. A party subpoena is issued to a person who is a party to the criminal case, such as a defendant, victim, or witness. Both types of subpoenas require the recipient to appear at a deposition and may also require them to bring certain documents or records.