A judge ruled Monday that two Williamson County prosecutors who worked on Michael Morton's 1987 murder trial must testify under oath.
The two former prosecutors will be asked why they didn't offer the defense certain evidence in the case.
Ken Anderson, who is now a district judge, and attorney Mike Davis filed a motion to quash the subpoena, but Judge Sid Harle refused their requests.
DNA evidence proved Michael Morton's innocence in his wife's murder earlier this month. He was released from prison after nearly 25 years behind bars.
Davis is expected to be deposed Tuesday in Georgetown.
Anderson has filed an appeal with the court of criminal appeals to overturn Judge Harle's decision and issue a stay to halt his testimony.
The court is expected to issue a decision before Anderson is scheduled testify on Oct. 31.