Selleneit's claim of self-defense is why one evaluator, Eric Nielsen, said he believed the man is unable to stand trial.
"He seems to be intent on defending himself based on psychotic symptoms," Nielsen said at the earlier hearing.
However, Kay said Thursday that he found John Malouf, a psychologist who evaluated Selleneit last year and found him to be competent, more credible than Nielsen.
"[Selleneit] doesn't have a great deal of sophistication, but he understands pleading guilty or not guilty," Malouf had said at the previous hearing. "He understands he needs to work with his attorney.
Defense attorney Julie George had said Selleneit has had delusions about being threatened with violence and about his wife being raped since at least the late 1990s. Selleneit believes his neighbor has "sex parties" with his wife while he is in the next room, and has said that "Eddie Van Halen comes into his mind and helps him occasionally," according to his attorney.
"Those are about as bizarre as I think a delusion can get," George said in court as she argued for Selleneit to be sent to the Utah State Hospital. "It's locking him into a belief system that makes it impossible for him to work with me."
Selleneit has been diagnosed with an "organic brain disorder with a labile affect, periodic delusional thought process, poor judgment [and] poor impulse control," according to court documents. As a teenager, Selleneit suffered a brain injury in a car crash, and doctors have said he is "mentally ill and very likely will be the rest of his life," court documents state.
According to previous testimony, Selleneit believed Pierce was having sex parties with his wife and was using crack cocaine to control her mind.
Selleneit claimed he heard his neighbor telepathically tell him, "We're having a sex party tonight. There will be cocaine. If you don't come, I'll kill you," according to Malouf.
A January trial has been set for Selleneit.
George said in court they don't anticipate any other plea besides "not guilty" at this time.
"There will definitely be issues with mental illness," she said.
Selleneit's wife, 54-year-old Melony Toone Selleneit is charged with illegally buying the weapon for her husband and then urging him to shoot the victim. She has been in the Utah State Hospital, and is scheduled for a six-month review early next month.