Ken Anderson -- who resigned in September as a Superior Court judge -- was Williamson County district attorney when he told a judge in 1987 he had no evidence that might help Michael Morton's defense.
Morton was convicted of killing his wife Christine and sentenced to life. He was released in 2011 after being cleared by DNA testing.
Mark Alan Norwood, who was convicted this year in the Morton killing, is also suspected of killing another woman in Bexar County in 1988.
Anderson reached an agreement Friday with prosecutors to settle criminal and civil complaints against him, the Austin (Texas) American-Statesman reported.
Prosecutors agreed to drop a tampering with evidence charge against Anderson and he will surrender his law license.
"It's a good day," Morton said. "I said the only thing that I want, as a baseline, is Ken Anderson to be off the bench and no longer practicing law and both of those things have happened, and more."
Barry Scheck of the Innocence Project, who fought for years to get DNA testing for Morton, said the group is working with Williamson County District Attorney Jana Duty to carry out an independent review of cases Anderson prosecuted in 15 years as district attorney. The Texas Criminal Defense Lawyers Association, the Innocence Project of Texas and Innocence Project of New York will carry out the review.