(JTA) — The suspect in a stabbing attack at a rabbi’s home in Monsey, New York, that left an elderly man dead has been deemed not mentally fit to stand trial by a federal judge.

The ruling released Monday found that Grafton Thomas currently cannot assist in his own defense because he is suffering from a mental disease.

U.S. District Judge Cathy Siebel in White Plains wrote that Thomas, 37, should be committed to a treatment facility for no more than four months to determine if he can reach “the capacity to permit criminal proceedings to go forward against him,” The Associated Press reported.

Thomas has pleaded not guilty to hate crimes charges in the Dec. 28 attack. He faces a total of 10 federal charges.

Thomas also was indicted on state charges, including attempted murder and burglary, and has pleaded not guilty. He remains in jail on $5 million bail. The judge in the state case has not yet ruled on Thomas’ competency to stand trial.

Federal prosecutors allege that Thomas targeted his victims because they were Jewish. They were attending a Hanukkah party at the rabbi’s home.

Josef Neumann, 72, who was injured in the stabbing when the knife penetrated his skull, remained in a coma after the attack and died last month.

Thomas’ attorney, Michael Sussman, has said that Thomas has suffered for many years from mental illness and may not have been taking his medication for depression and psychosis before the attack, CBS News reported.

Police who searched Thomas’ home after the attack found handwritten journals that they say expressed anti-Semitic views, including references to Adolf Hitler and ‘Nazi culture.’ He also had searched online on his cellphone for “German Jewish Temples near me” and “Zionist Temples” in Elizabeth, New Jersey, and on Staten Island.