Dimitrios Pagourtzis, 19, was transferred Thursday morning from the Galveston County Jail to the North Texas State Hospital in Vernon, officials confirmed.
Last month, a judge ruled Pagourtzis was incompetent to stand trial.
He was ordered "committed to and confined" to a Texas Department of State Health Services facility, the ruling states. The treatment may not exceed 120 days.
Tour the hospital where accused killers receive mental health treatment
Over that time period, he will be evaluated and treated to make him fit to stand trial. With the ruling, he won't be allowed to refuse treatment.
The order states Pagourtzis is unfit for trial as of Oct. 18. The trial, which was moved to Fort Bend County, was set to begin in February 2020.
Earlier in November, the suspect's lawyers indicated that he was likely to be declared incompetent for trial.
Pagourtzis' mental state has been the focus of several discussions between prosecutors and defense attorneys since the shooting that killed 10 and injured 13 others.
In August, attorneys for Pagourtzis said his mental state had deteriorated to the point that he doesn't understand the case before him.
If convicted, he faces life in prison with the possibility of parole after 40 years.
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