(CNN) The Texas teen accused of killing 10 people at Santa Fe High School last year will be declared not competent to stand trial, his defense attorney said Monday.

Dimitrios Pagourtzis was evaluated by three experts: one hired by the defense, an independent expert and one chosen by state prosecutors. All three agreed that the teen is not competent to stand trial, attorney Nicholas Poehl said.

The judge still needs to rule, but Poehl said he believes that's basically a formality.

"The state had the option of putting this issue before a jury, but when their own expert agreed, the state very graciously agreed to not contest it," Poehl said.

The Galveston County district attorney was not immediately available for comment.