Editor's note: This story has been updated to include comments from Judge Ken Anderson, state Sen. Rodney Ellis and lawyers for Michael Morton.

Williamson County state district Judge Ken Anderson, who oversaw the wrongful murder conviction of Michael Morton in 1987, submitted a letter to Gov. Rick Perry on Monday resigning his position effective immediately.

Anderson is facing both civil and criminal court proceedings for his role in prosecuting Morton for the 1986 murder of his wife, Christine Morton. Attorneys for Morton allege that Anderson withheld critical evidence that pointed to Morton's innocence and that he lied to the judge about the existence of that evidence. Morton was sentenced to life in prison and spent nearly 25 years behind bars before DNA testing revealed that he was innocent and connected another man to his wife's killing. He was released from prison in 2011.

In a statement, Anderson made no reference to the Morton case and thanked his supporters. For the "foreseeable future" he said he would be focused on "making the transition into private life."

"There comes a time when every public official must decide that it is time to leave public life," Anderson said in the statement released by his lawyer, Eric Nichols. "For me and my family, that time is now."

Morton's lawyers, John Raley of the Houston law firm Raley & Bowick, and Barry Scheck of the New York-based Innocence Project, said Anderson's resignation was "long overdue."

"We look forward to an adjudication of the pending disciplinary action brought by the state bar as well as the pending criminal charges," they said in an emailed statement. "Judge Anderson deserves a fair trial, but if there are findings against him in either proceeding, we would expect that appropriate penalties be imposed.”

Anderson was appointed to the bench by Gov. Rick Perry in 2002 and the State Bar of Texas named him “Prosecutor of the Year” in 1995. Perry responded to Anderson on Monday with a letter accepting the resignation and thanking the longtime prosecutor and judge for his service.

The State Bar filed a disciplinary case against Anderson last year, and the trial is scheduled to begin on Monday in Williamson County. Anderson could be disbarred if he is found to have violated professional rules of conduct in securing Morton's wrongful conviction.

Anderson is also facing criminal charges after Tarrant County state district Judge Louis Sturns, following a court of inquiry in February, charged the former prosecutor with tampering with government records (a misdemeanor), tampering with physical evidence (a felony) and failing to comply with a judge's order to turn over such evidence, for which he could be held in “contempt of court.”

Anderson has said that he regrets the errors of the justice system in Morton’s case. But he has maintained that he committed no wrongdoing in the prosecution.

During their investigation of Morton's case, Raley, of the Houston law firm Raley & Bowick, along with Barry Scheck and Nina Morrison of the New York-based Innocence Project, discovered evidence that they allege Anderson deliberately withheld from defense lawyers and from the judge in the case.

Among the items was a transcript of a phone call in which Morton’s mother-in-law recounted to police a conversation with her 3-year-old grandson, who said he saw a “monster” beat his mother to death. He said Morton, his father, was not at home when the beating happened. They also found reports from neighbors who told police that they saw a man in a green van park near the Mortons' home and walk into the nearby woods several times before the crime.

The State Bar conducted a 10-month investigation after a grievance was filed against Anderson in the case. The State Bar’s Commission for Lawyer Discipline wrote in its court filing that Anderson knew of the evidence and withheld it. The filing also alleged that Anderson made a false statement to the court when he told the judge he had no evidence that could be favorable to Morton’s claims of innocence.

His conduct, the State Bar commission wrote, violated five of the state’s Disciplinary Rules of Professional Conduct.

A spokeswoman for the State Bar did not immediately respond to a phone call requesting comment.

State Sen. Rodney Ellis, D-Houston and chairman of the Innocence Project, said that Anderson's resignation was appropriate and that he had concerns about the judge continuing to oversee cases while the legal proceedings against him were pending. Ellis said officials in Williamson County ought to implement a review process to examine cases that Anderson worked on while he was a prosecutor to discover whether there were other "miscarriages of justice."

Texas Tribune donors or members may be quoted or mentioned in our stories, or may be the subject of them. For a complete list of contributors, click here.