Jon Schaffer, 53, a member of the Oath Keepers militia group, pleaded guilty to two charges - obstruction of an official proceeding and entering a restricted building with a dangerous weapon.

Schaffer, who is also a heavy metal guitarist in the band Iced Earth, had originally faced six charges including using a chemical irritant designed for grizzly bears on police officers during clashes.

He turned himself to FBI agents in Indiana two weeks after his arrest, and after a photo of him inside the Capitol wearing a hat reading "Oath Keepers Lifetime Member" appeared on the front pages of US newspapers.

He is facing 30 years in prison and is expected to co-operate with investigators.

Investigators for the District of Columbia says they have identified over 540 suspects and charged some 400 people in connection with the Capitol siege.

Just weeks after the rampage in January, FBI officials said they had already been inundated with 140,000 videos and photos from members of the public.

Officials say they are considering filing serious charges of seditious activity against some individuals who were involved in the siege on the Capitol.

According to federal criminal code, seditious conspiracy means an effort to conspire to overthrow the US government. The punishment is severe: up to 20 years in prison.

Capitol riot: Prosecutors get first guilty plea 100 days after attack

https://www.bbc.co.uk/news/world-us-canada-55626148

Jon Schaffer, pictured wearing a blue jacket, was seen in news photos taken during the riot