Heavy metal guitarist is first capitol rioter to plead guilty and help the authorities

The alleged rioter has been released from prison as part of his agreement

A heavy metal guitarist who wore a "lifetime member" Oath Keepers gang hat during the Capitol riot has pleaded guilty to storming the federal building and has reportedly agreed to work with authorities.

Jon Ryan Schaffer, from Indiana, entered two guilty pleas when he appeared in federal court on Friday, reports USA Today.

He was charged with felony counts of obstruction of an official proceeding, and entering and remaining in a restricted building or grounds with a deadly or dangerous weapon.

Mr Schaffer's agreement to work with the government may provide investigators a key pathway into developing broader conspiracy charges against right wing gangs like the Oath Keepers and Proud Boys.

FBI Director Chris Wray described the ongoing investigation into the Capitol insurrectionists as one of the largest since the 9/11 terrorist attacks.

Mr Schaffer's plea is the first guilty plea associated with the 6 January attacks.

According to prosecutors, Mr Schaffer wore a tactical vest and carried bear spray into the Capitol on the day of the attack, and was at the head of a crowd of rioters pushing past Capitol police officers.

“Schaffer admitted to being among the first individuals to push past the damaged doors and into the Capitol building, forcing officers to retreat,” according to a Justice Department news release. “Schaffer and others advanced toward five or six backpedaling USCP officers while members of the mob swelled inside of the Capitol and overwhelmed the officers. The officers ultimately deployed a chemical irritant to disperse the mob.”

According to prosecutors, Mr Schaffer is a "lifetime and founding" member of the Oath Keepers, a right wing extremist gang that presents itself as a militia, but does not have the backing of any state. Twelve other members of the gang have been charged with conspiring to carry out the attacks on the Capitol.

Mr Schaffer has not been charged yet. The obstruction charges carry a maximum 20 year prison sentence, while his weapons charge carries a maximum 10 years in prison.

He was originally arrested on six charges in January, but four of those charges have since been dropped.

Mr Schaffer has also been granted release from prison, and will be given the freedom to travel throughout the continental US, though he is banned from carrying a firearm, including any he may already own.