Originally Published: 02 MAY 22 12:06 ET

Updated: 02 MAY 22 12:58 ET

By Holmes Lybrand

(CNN) -- A former New York City police officer was convicted Monday of assaulting a Washington, DC, police officer during the January 6 riot at the US Capitol.

Thomas Webster, who claimed he was defending himself when he swung a metal flagpole at police and tackled one to the ground, choking him by his chin strap, was convicted by a jury on all six charges after roughly two hours of deliberations.

The 56-year-old ex-NYPD officer and former Marine faces a maximum of 20 years in prison for the assault of DC officer Noah Rathbun. Webster is the fourth January 6 rioter to be convicted by a jury and the first to be convicted by a jury in a police assault case from the insurrection.

"This case is about rage," one of the prosecutors, Brian Kelly, said in closing arguments Friday.

Kelly told the jury that while Webster "wants to blame officer Rathbun," it was Webster who first attacked Rathbun and Webster who crossed police lines to tackle the officer.

"His actions speak for themselves," Kelly concluded, asking the jury to find Webster guilty on all charges, including assaulting, resisting or impeding an officer with a dangerous weapon.

Webster's defense attorney, James Monroe, argued that Webster only acted in self-defense after being punched by Rathbun.

"Are we ever going to accept police misconduct?" Monroe asked the jury. "We're dealing with a bad cop," he said of Rathbun, adding that Webster "knows what a bad cop looks like" from serving on the NYPD for two decades.

This the first case where a Capitol rioter claimed self-defense. In other related cases, jurors previously rejected attempts by defendants to shift the blame onto then-President Donald Trump. Most of the January 6 cases that have gone to trial so far resulted in convictions.

The self-defense claim gained no traction with jurors.

Doris Spruell, a juror, told reporters after the verdict that they "looked at all the evidence...and felt that there was no grounds for self-defense. The video, I think, clearly showed that."

When asked about Webster's testimony, Spruell said she "did not think it was credible."

"The case that the government laid out was very comprehensive," another juror said, adding that he felt "quite comfortable with the verdict" and that the jury didn't find Webster's testimony compelling.

"It was very quick and very obvious," another juror said.

While prosecutors requested Webster be locked up immediately, Mehta allowed Webster to remain on 24-hour home confinement with an ankle monitor, a decision he said was "a close call."

Webster, who sat still during the verdict, left the DC courthouse holding a flip phone to his ear and did not speak with reporters.

"It's a difficult day for Tom Webster and his family," Monroe said. "We're going to give some thought about the result today and decide where to go from here."

This story has been updated with comment from jurors.