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.

Violent Attacks on Police Officers

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.”

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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.

Apology and Sentencing Recommendations

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.”

“It makes him a statistic,” she said. “It doesn’t consider the person he is, how much he has grown.”

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Detailed Account of Attacks

Dempsey was wearing a tactical vest, a helmet and an American flag gaiter covering his face when he attacked police at a tunnel leading to the Lower West Terrace doors. He shot pepper spray at Metropolitan Police Department Detective Phuson Nguyen just as another rioter yanked at the officer’s gas mask.

“The searing spray burned Detective Nguyen’s lungs, throat, eyes, and face and left him gasping for breath, fearing he might lose consciousness and be overwhelmed by the mob,” prosecutors wrote.

Dempsey then struck MPD Sgt. Jason Mastony in the head with a metal crutch, cracking the shield on his gas mask and cutting his head.

“I collapsed and caught myself against the wall as my ears rang. I was able to stand again and hold the line for a few more minutes until another assault by rioters pushed the police line back away from the threshold of the tunnel,” Mastony said in a statement submitted to the court.

Dempsey has been jailed since his arrest in August 2021.

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History of Political Violence

His criminal record in California includes convictions for burglary, theft and assault. The assault conviction stemmed from an October 2019, gathering near the Santa Monica Pier, where Dempsey attacked people peacefully demonstrating against then-President Donald Trump, prosecutors said.

“The peaceful protest turned violent as Dempsey took a canister of bear spray from his pants and dispersed it at close range against several protesters,” they wrote, noting that Dempsey was sentenced to 200 days of jail time.

Dempsey engaged in at least three other acts of “vicious political violence” that didn’t lead to criminal charges “for various reasons,” according to prosecutors. They said Dempsey struck a counter-protester over the head with a skateboard at a June 2019 rally in Los Angeles, used the same skateboard to assault someone at an August 2020 protest in Tujunga, California, and attacked a protester with pepper spray and a metal bat during a August 2020 protest in Beverly Hills, California.

More than 1,400 people have been charged with Jan. 6-related federal crimes. Over 900 of them have been convicted and sentenced, with roughly two-thirds receiving terms of imprisonment ranging from a few days to the 22 years that Tarrio received.