A QAnon conspiracy theorist who led a pack of Donald Trump supporters that chased a solitary police officer around the US Capitol on the day of the January 6 attack has been found guilty of several felonies.

Douglas Jensen – the bearded 43-year-old Iowa man who appeared in several media photos of the attack while wearing a black T-shirt with a large “Q” – could in theory face more than 50 years in prison after a federal jury in Washington DC convicted him on Friday, US justice department prosecutors said in a statement.

However, it is rare for convicts in US district court to receive the harshest available punishment, even if they chose to stand trial rather than plead guilty in advance. And the harshest sentence handed out so far to anyone found guilty of having a role in the deadly Capitol attack has been 10 years.

Prosecutors alleged that Jensen formed part of the mob of Trump supporters who gathered at the Capitol on the day in early 2021 that Congress was meeting to certify Joe Biden’s victory over Trump in the previous year’s presidential election.

Clad in a navy blue knit cap and the T-shirt paying homage to QAnon, the conspiracy myth that Trump is locked in secret combat against a cabal of leftist pedophiles and its deep state allies, Jensen scaled a wall at the Capitol, watched as fellow mob members broke the Senate wing entrance’s windows and doors, and was among the first 10 people to invade the facility, according to prosecutors.

Jensen went around a few corners and joined a crowd that encountered a lone Capitol police officer near a stairwell, prosecutors said. Jensen squeezed his way to the front of the group, essentially came face to face with the officer, Eugene Goodman, and helped chase him up the stairs to a hallway just outside the Senate chamber.

Prosecutors said that Jensen – carrying a knife with a three-inch blade in his pocket – barked at Goodman as well as other officers to “back up” and ordered them to arrest Trump’s vice-president, Mike Pence, whom the mob was threatening to hang if he didn’t halt the certification of Biden’s electoral college win.

After 40 minutes, Jensen was made to exit, briefly re-entered another section of the Capitol and was forced out again, prosecutors said.

Authorities arrested him two days later, after he returned to Iowa.

At Jensen’s trial, concluding Friday, his defense attorney portrayed him as “a terribly confused man” whose mind was even more twisted by QAnon as well as Covid lockdowns. Jensen’s attorney also claimed his client had never physically hurt anyone during his time at the Capitol.

But jurors needed just four hours to convict Jensen as charged of assaulting police, obstructing a congressional proceeding, interfering with law enforcement, entering a restricted building and disorderly conduct with a dangerous weapon, which are all felonies.

Jensen was also found guilty of a pair of misdemeanors: picketing in the Capitol and disorderly conduct in that facility.

Goodman testified during Jensen’s trial, describing how he had felt cornered and threatened by the mob. Prosecutors showed video of Goodman leading the mob away from the Senate floor while defensively holding up a baton with one of his hands.

The Senate awarded Goodman a congressional Gold Medal, saying that the officer had led the violent mob away from lawmakers who ultimately did certify Trump’s defeat in the 2020 election.

A bipartisan Senate report linked seven deaths to the Capitol attack and said it had left more than 140 police officers injured. As of this week, more than 870 people had been charged with roles in the insurrection.