COLORADO SPRINGS, Colo. — Robert L. Dear Jr. thought “the feds” had been after him for 20 years, cutting holes in his clothes and planting a listening device in his pickup truck. He believed President Obama was the Antichrist, and that the Planned Parenthood center he admitted firing on in November was the most evil place in the world.

Those delusions and Mr. Dear’s mental state were detailed in a courtroom here on Thursday as lawyers heard testimony about whether Mr. Dear was mentally competent to stand trial for killing three people and wounding nine. Two state psychologists who examined him this winter testified that they believed he was not.

The decision rests with the district judge overseeing the case, Gilbert Martinez. He did not make a ruling on Thursday, and after a day of testimony, carried the hearing over until May 10.

Jackie Grimmett, one of two state psychologists who examined Mr. Dear this winter, said he suffered from widespread and long-running delusions that shaped his view of reality. He believed the F.B.I. had been pursuing him for years, and believed that the judge and his defense lawyers were part of a conspiracy to silence him.