At a hearing Friday, Mark Castillo said he wants to represent himself, the Baltimore Sun reported. Judge Gale Rasin said court psychiatrists must first determine whether Castillo is competent to stand trial and that she will make a decision in 10 days.

Rasin told Castillo he has shown little legal knowledge and would be "at a serious disadvantage" trying to represent himself.

Investigators say Castillo drowned his children -- Anthony, 6, Austin, 4, and Athena, 2 -- at the Baltimore Marriott Inner Harbor at Camden Yards hotel in March and then tried to kill himself by swallowing Motrin. He allegedly killed the children to get even with his wife, Dr. Amy Castillo, who lives in a Washington suburb in Maryland, during a dispute about custody and divorce.

Dr. Castillo had warned authorities in Montgomery County that her husband had made threats to kill the children.

Public Defender Natasha Moody entered a plea of "not criminally responsible" for Castillo this year but has since withdrawn it.