The Pennsylvania conspiracy theorist accused of beheading his father and showing it in a sick YouTube video claimed that his dad had “betrayed” him by working for the federal government — and that he had to die.

Justin Mohn, 32, of Levittown, appeared in court on Tuesday and revealed that a nonsense conspiracy theory motivated him to commit the heinous crime, local NBC 10 reports.

“I and a lot of other people around America believe that the federal government has betrayed America, they are destroying the country and we have to do something to take our country back,” Mohn told reporters as he was escorted by police.

When pressed on how exactly the murder and decapitation of his father, Michael Francis Mohn, 68, would further his goal, the suspect claimed his murdered dad was part of the problem.

“He was a federal employee and betrayed me,” he said. “I was trying to perform a citizen’s arrest. He resisted that citizen’s arrest.

The elder Mohn worked as an engineer the U.S. Army Corps of Engineers’ Philadelphia office.

“It’s lawful to use deadly force in that event,” he added.

Justin Mohn faces a slew of charges, ranging from first-degree murder and abuse of a corpse to making terrorist threats and robbery.

Prosecutors said Mohn had planned to kill his father on Jan. 30, with the suspect allegedly preparing a speech for his YouTube video titled “Mohn’s Militia – Call to Arms for American Patriots.”

The video, which showed off his dad’s severed head, twice, was allegedly a call for people to join Mohn in overthrowing the US government, as well as capturing and killing federal agents and judges. 

“Essentially what this case is, Mr. Mohn, based on his beliefs, is making a call to arms to achieve the aims he believes in, ” prosecutor Edward Louka told the court. 

“He did that through violence. The violence was the murder of his father, who, it’s obviously not a coincidence, was a federal employee,” Louka added. 

“He, essentially, needed that murder to get his message across.”

Prosecutors also revealed that rather than apologize for his father’s death, Mohn only wrote an apology letter to the National Guard base at Fort Indiantown Gap, where he was captured while carrying a loaded gun. 

Mohn’s defense attorney, Steven Jones, did not argue the murder charges but instead sought to get the terrorism charges dismissed as his client had no real backing over his call to arms. 

“It’s a tragic case,” Jones told NBC 10. “I don’t think there are any winners here.” 

Mohn was declared competent to stand trial last month, with the suspect scheduled to return to court on Oct. 11 for his formal arraignment.