Judge Stephen Corr ruled from the bench after a nearly five-hour proceeding that unfolded with Justin Mohn, wearing a yellow jumpsuit with "inmate" printed on the back and with his hands cuffed in front of him, seated in court and smiling, nodding or shaking his head throughout testimony.
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Corr also granted Mohn's wish to dismiss his public defender and appoint a different attorney to handle the case. Asked whether he'd be willing to work with a new attorney, Mohn responded: "Absolutely."
The ruling means the case, which captured headlines with Mohn's arrest at a National Guard base two hours from his and his parents' Levittown home and after the gruesome video had already been viewed numerous times online, will go forward.
The hearing had several surreal moments, with Mohn nodding along and smiling widely at prosecution witness Dr. Kelly Chamberlain, a forensic psychologist, who testified that she found Mohn in her two meetings with him to be intelligent, calm and socially appropriate.
Chamberlain testified that Mohn apparently objected to his attorney's strategy of using a mental health defense and that he seemed appropriately "self-interested."
She disputed the findings of defense expert witness Dr. John Markey, who said he had met with Mohn four times and determined at first that he had schizophrenia, but on Thursday said it was delusional disorder instead. He pointed specifically to Mohn's letters in which he said he claimed to be the messiah, a King David-like figure whom the federal government was persecuting.
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Mohn came to believe his own public defender was a federal agent working against him, Markey said, and he wrote a letter to Russia's ambassador to the United States seeking to strike a deal to give Mohn refuge and apologizing to President Vladimir Putin for claiming to be the czar of Russia.
"It's all delusional," Markey said.
Chamberlain said she didn't believe he meant to say he was the messiah, and that his writings in fact said "Satanic" cults within the U.S. think he's the messiah.
"I believe it could be construed as delusional," she said, but added that his writing was part of his rhetoric. "He feels people like him have been kind of screwed over."
Mohn nodded agreeably during her testimony.
Another prosecution witness, corrections officer Ralph Taylor, said Mohn was "extremely polite" and respectful in jail.
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Corr questioned him at the start of the proceedings, asking him if he knew why he was there, and Mohn recounted that he was facing a number of charges, the "most serious" of which were first-degree murder charges.
All that added up, prosecutors said, to someone able to participate in his own legal defense.
According to prosecutors, Mohn fatally shot his father with a pistol and then used a kitchen knife and machete to decapitate Michael Mohn at the Levittown house where they both lived.
Justin Mohn then recorded a video in which he held up his father's head and identified him as a 20-year federal employee, while calling for violence against the government. Prosecutors have said they found blood stains on the desk in the room where the video was recorded along with a computer that had several tabs open, including one for YouTube.
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In the video, Justin Mohn also espouses a variety of conspiracy theories and rants about the Biden administration, immigration and the border, fiscal policy, urban crime and the war in Ukraine.
The video was posted on YouTube for several hours before it was taken down.
Justin Mohn faces charges of first-degree murder, abusing a corpse and possession of instruments of crime. He is being held without bail.
The Associated Press contributed to this report.