A federal judge sentenced a former employee of the Argonne National Laboratory Wednesday to 18 months in prison after he admitted to assaulting law enforcement officers during the Jan. 6, 2021, riot.In July, Robin Lee Reierson, 69, of Schiller Park, pleaded guilty to a felony charge of assaulting, resisting or impeding certain officers. He was among a group of rioters gathered in the West Plaza of the U.S. Capitol building, according to court documents.Reierson used his body to push against a bike rack barrier and into a line of police officers, the documents said. He also pushed against the officers by using both of his hands and by lowering his shoulders. At one point, he tried to take hold of an officer's baton.He eventually left the West Plaza but told other rioters, “Don’t stop, keep going,” and "Put the cameras down, keep going," according to a statement from the U.S. attorney’s office for the District of Columbia.U.S. District Judge Reggie B. Walton in Washington, D.C., handed down the sentence. He also gave Reierson 36 months of supervised release and ordered him to pay $7,000 in restitution and fines.About a week after the attack on the Capitol, someone sent a tip to the FBI that an employee of Argonne National Laboratory was possibly involved in the riot. Reierson was employed as a lead welder at Argonne for more than 40 years.The FBI matched images from videos to Reierson’s Illinois driver’s license and began surveillance of his home. Agents observed him leaving in a cargo van with the same Illinois license plates that tollway records indicate was driven to Washington, D.C., on Jan. 5, 2021, and back to Illinois on Jan. 7, 2021. The FBI arrested Reierson Aug. 23, 2023.He was initially charged with assaulting an officer, obstruction of law enforcement, entering a restricted building and engaging in disorderly conduct with the intent of impeding Congress.Reierson is one of nearly 50 known Illinois residents to face federal criminal charges connected to the Jan. 6 attack. More than 1,500 people have been charged in connection with the attack in almost all 50 states.Contributing: Sophie Sherry, Jon Seidel