WASHINGTON – A California man with a history of political violence was sentenced on Friday to 20 years in prison for repeatedly attacking police with flagpoles and other makeshift weapons during the Jan. 6, 2021, riot at the U.S. Capitol.

David Nicholas Dempsey’s sentence is among the longest among hundreds of Capitol riot prosecutions. Prosecutors described him as one of the most violent members of the mob of Donald Trump supporters that attacked the Capitol as lawmakers met to certify Joe Biden’s 2020 presidential election victory.

Dempsey, who is from Van Nuys, stomped on police officers’ heads. He swung poles at officers defending a tunnel, struck an officer in the head with a metal crutch and attacked police with pepper spray and broken pieces of furniture, prosecutors said.

He climbed atop other rioters, using them like “human scaffolding” to reach officers guarding a tunnel entrance. He injured at least two police officers, prosecutors said.

“Your conduct on January 6th was exceptionally egregious,” U.S. District Judge Royce Lamberth told Dempsey. “You did not get carried away in the moment.”

Dempsey pleaded guilty in January to two counts of assaulting police officers with a dangerous weapon.

Only former Proud Boys leader Enrique Tarrio has received a longer sentence in the Jan. 6 attack. Tarrio was sentenced to 22 years for orchestrating a plot to stop the peaceful transfer of power from Trump to Joe Biden after the 2020 presidential election.

Dempsey called his conduct “reprehensible” and apologized to the police officers whom he assaulted,

“You were performing your duties, and I responded with hostility and violence,” he said before learning his sentence.

Justice Department prosecutors recommended a prison sentence of 21 years and 10 months for Dempsey, a former construction worker and fast-food restaurant employee. Dempsey’s violence was so extreme that he attacked a fellow rioter who was trying to disarm him, prosecutors wrote.

“David Dempsey is political violence personified,” Assistant U.S. Attorney Douglas Brasher told the judge.

Defense attorney Amy Collins, who sought a sentence of 6 years and six months, described the government’s sentencing recommendation as “ridiculous.”