A man accused of beheading his father in suburban Philadelphia and posting a gruesome video on social media that shows him holding up the severed head has been charged with first-degree murder and abusing a corpse.

Justin Mohn was armed and had jumped a fence at a National Guard facility about 161km away when he was arrested, hours after the killing.

The father, identified as Michael Mohn, was found beheaded in the bathroom of his home in Levittown, where court records said his 32-year-old son also lived. Police said Justin Mohn was taken into custody at Fort Indiantown Gap.

Police said Michael Mohn’s wife, Denice Mohn, arrived home and found the body about 7pm on Tuesday (local time). Officers found Mohn’s body, a machete and bloody rubber gloves, according to a police affidavit. Denice Mohn told police her husband’s white Toyota Corolla and her son were missing.

Police said the YouTube video, which was more than 14 minutes long, showed Justin Mohn picking up his father’s decapitated head and identifying him by name. Police said it appeared Mohn was reading from a script as he railed about the government.

In a statement, YouTube said the video, which was uploaded and not livestreamed, was removed for violating its graphic violence policy and Mohn’s channel was shut down.

Mohn embraced violent anti-government rhetoric in writings he published online going back several years. In August 2020, Mohn published an online “pamphlet” in which he tried to make the case that people born in or after 1991 — his birth year — should carry out what he termed a “bloody revolution”. He also complained at length about a lawsuit that he lost, and encouraged assassinations of family members and public officials.

In the video posted after the killing, he described his father as a 20-year federal employee and said: “He is now in hell for an eternity as a traitor to his country.”

He also espoused a variety of conspiracy theories and rants about the Biden administration, immigration and the border, fiscal policy, urban crime and the war in Ukraine, calling for violence against other federal employees.

Mohn then drove his father’s car to Fort Indiantown Gap, where he was taken into custody.

Officials at Fort Indiantown Gap were told that Mohn’s cellphone had pinged nearby and investigators caught up with him inside the National Guard base, where he was walking after having apparently jumped the fence. He had a gun when he was caught.

The house where the body was found is in a suburban development of single-family homes.

Neighbours out walking dogs the morning after the incident described Justin Mohn as a regular walker in the development, someone they recognised and described as weird.

Bart DeHaven said he was forced to call police several times after Justin Mohn sat on a raised manhole cover in a park directly across the street from his home and stared at his house.

“It’s just sad,” DeHaven said. “He should have got some kind of help.”

Carrie McCarthy said she saw him walking frequently and sitting in the wooded area in the neighbourhood. She said someone sent her the YouTube video, which left her stunned.

“I screamed. I totally screamed,” she said. “I opened the video and I was like, ‘Oh my God, that’s the guy I see every day, and I knew something was unhinged with him.’”

A man who lived in apartments with Mohn about a decade ago in Colorado Springs, Colorado, recalled hearing Mohn talk at length about conspiracy theories. Davis Rebhan said he left the living situation shortly after Mohn became volatile one night and damaged the walls and other objects.

Mohn’s only visitor during the year they lived together was his father, who visited for a weekend, Rebhan said.

“I got nothing from that visit that would have made me ever think this would happen,” Rebhan said. “There was nothing that would lead me to believe that Justin didn’t care about his dad. And it was really clear that his dad cared about him because it was clear he had these issues and his dad still came across the country to stay with him.”

Mohn, who also was arrested on a weapons possession charge, was arraigned and held without bail. He is scheduled for a hearing on February 8. The district court office said it had no record of a lawyer representing him.

– Additional reporting, NZ Herald