Ashton Kutcher has resigned from his nonprofit organisation Thorn after coming under fire for expressing support for Danny Masterson ahead of his sentencing for rape.
Masterson was sentenced to 30 years to life in prison earlier this month after he was convicted on charges of raping two women relating to incidents in the early 2000s.
Kutcher and his wife Mila Kunis received backlash after it emerged they were among more than 50 people who wrote to the judge to ask for leniency when sentencing their That '70s Show co-star.
The actor announced his resignation from Thorn, the organisation he co-founded to fight child sexual abuse, in a letter to its board on Thursday.
"I have determined the responsible thing for me to do is resign as chairman of the board, effectively immediately," Kutcher wrote in the letter, which was shared on Thorn's website on Friday. "I cannot allow my error in judgment to distract from our efforts and the children we serve."
He continued, "Victims of sexual abuse have been historically silenced, and the character statement I submitted is yet another painful instance of questioning victims who are brave enough to share their experiences. This is precisely what we have all worked to reverse over the last decade."
Kutcher, 45, co-founded Thorn in 2009 with his first wife Demi Moore. Representatives for the organisation expressed gratitude to the No Strings Attached star for his participation over the years.
"We would not be the Thorn that we are today without Ashton's contributions," they stated on its website.
Shortly after their character letters were made public, Kutcher and Kunis issued a public apology video in which they insisted Masterson's family asked them to write the statements, which were only intended for the judge.
"We support victims. We have done this historically through our work and will continue to do so in the future," Kunis insisted. "The letters were not written to question the legitimacy of the judicial system or the validity of the jury's ruling."
She added, "Our heart goes out to every single person who's ever been a victim of sexual assault, sexual abuse or rape."