Andrea Yates, Who Drowned Her 5 Kids in a Tub in 2001, Annually Declines Release from Mental Hospital

At the time of the murders, it was determined that Yates suffered from postpartum depression, postpartum psychosis and schizophrenia. Now 57, she continues to undergo mental health treatment

Nearly 21 years ago, Andrea Yates horrified the nation when she confessed to drowning her five young children in the bathtub of their suburban Houston home on June 20, 2001.

Yates, who was 37 years old at the time, suffered from severe postpartum depression, postpartum psychosis and schizophrenia. According to court testimony, she waited for her husband, Rusty, to go to work. When he was gone, she began to drown her children one by one.

After she drowned the children, she called 911 repeatedly and then called her husband and told him to come home from work.

Yates was charged with five counts of capital murder. Her high-profile 2002 trial made national news. It was broadcast live and even landed on the cover of PEOPLE.

But despite the fact that Yates confessed to the killings, the complex case had several twists and turns.

For more on Andrea Yates, listen below to our daily podcast PEOPLE Every Day.

The prosecution pushed for the death penalty and primarily focused on the victims: Noah, 7; John, 5; Paul, 3; Luke, 2; and Mary, 6 months. But the defense contended that Yates' depression and psychosis caused her to kill her kids, and argued that she needed intensive mental health treatment rather than incarceration.

Getty.

Her husband, Rusty, initially stood beside her. "She loved those kids," Rusty said to the crowd of media in 2001. He later divorced Yates and remarried.

A 2002 jury convicted her of capital murder, but sentenced her to life in prison with the possibility of parole after 40 years. Yates' attorneys successfully appealed the case and the verdict was overturned. After a 2006 retrial, Yates was found not guilty by reason of insanity.

Brett Coomer/AP

Since January 2007, Yates has been at Kerrville State Hospital, a mental facility in Kerrville, Texas. Although she was remanded to the mental facility more than 15 years ago, Yates can undergo a review every year to see if she is competent to leave the facility.

Now 57, Yates opts each year to waive her right to be reviewed. PEOPLE confirms that she has never undergone review, choosing instead to continue treatment. Details of her treatment have not been released.

Her defense attorney, George Parnham, keeps in contact with Yates and says that Yates is "happy" in the facility.

"She's where she wants to be. Where she needs to be," Parnham told ABC News last year. "And I mean, hypothetically, where would she go? What would she do?"

Parnham previously told PEOPLE that Yates "grieves for her children" every day, often watching home videos of the kids who she killed. She also spends her time making aprons, cards and gifts in the craft room and anonymously selling them. The money goes to the Yates Children Memorial Fund, which was founded by Parnham and his wife Mary and dedicated to women's mental health, particularly postpartum mental health.