A man accused of assaulting a police officer at the Capitol on Jan. 6 alleges that two guards at the D.C. jail beat him last month, breaking his nose, dislocating his jaw and leaving him suffering seizures.

An attorney for Ryan Samsel, 38, detailed the allegations in an interview Tuesday, saying he has been told the incident is under investigation by the jail and federal authorities.

“This is unjustified, and the way that these guys are being treated is completely unreasonable, it’s wholly unconstitutional,” the attorney, Steven Metcalf, said. “It doesn’t matter what these guys are being charged with. All of these guys are still pretrial detention; they have not been convicted of any crimes. And this is what they’ve been forced to endure.”

In a statement, the D.C. Department of Corrections said the jail “takes the safety and well-being of all residents, staff, and contractors extremely seriously. We are aware of the allegation made by an inmate and it is under investigation by the Department of Justice.”

Lira Gallagher, a spokeswoman for the FBI’s Washington Field Office, said the bureau “is aware of the allegations; however, as a matter of policy, we can neither confirm nor deny the existence of an investigation.”

According to Metcalf, the incident, as related to him by his client, began the afternoon of March 20 when Samsel complained that the guards had taken hours to get him toilet paper. An argument ensued. That evening, according to Metcalf, Samsel was moved to another cell. Around midnight, the lawyer said, two guards came to that cell, restrained Samsel’s arms behind his back with zip-tie handcuffs and “beat him to a bloody pulp.”

Samsel did not regain consciousness until the next day, according to Metcalf, and has since suffered seizures for the first time in his life. His nose was allegedly broken, his jaw dislocated and his vision in one eye damaged. Metcalf said he saw Samsel by video two weeks later, and his client’s face was still black and blue and the skin around his wrists stripped off.

Metcalf, who is representing other alleged rioters, said he heard of the alleged beating from them and has spoken to other inmates, as well. A second attorney for Samsel, Elisabeth Pasqualini, said she separately learned of the alleged incident from attorneys for other defendants in the unit.

Metcalf said he is in the process of learning the facts, including seeking Samsel’s medical records, and had not reported the incident to police. But he said his client complained at the jail. According to one of Samsel’s other attorneys, he has been transferred to a different facility.

Samsel has been in detention since his arrest in late January. The Bucks County, Pa., resident is accused of using a barricade to push an officer outside the Capitol to the ground, knocking her unconscious.

According to prosecutors, Samsel then helped the officer back up and said, “We don’t have to hurt you. Why are you standing in our way?” She later collapsed while arresting another rioter and went to an emergency room, where she was told she suffered a concussion.

Later, according to court records, Samsel attempted to take a riot shield from an officer.

Samsel was on parole at the time of the riot in an assault case, according to court documents. Details of that case were not immediately available.

In connection with the Jan. 6 riot, he is charged with assault on a police officer, obstruction of justice and impeding law enforcement. He has not contested his detention.

Other inmates have complained through attorneys about conditions in the D.C. Central Detention Facility, but no others have alleged assaults by the guards. Samsel’s allegation was first raised by another alleged rioter, Ronald Sandlin, who told Magistrate Judge Dabney L. Friedrich on Tuesday that he was afraid to stay in the jail after what happened to Samsel. He said he had been “threatened with violence by the staff here” and that “even making this statement is putting me in danger of violence and retaliation.”

Metcalf said other inmates have told him guards have brought up Samsel’s alleged beating as an example of what will happen to them if they cause trouble.

“They don’t like what they’ve done, they don’t like how they’ve questioned what’s going on, they don’t like how they’ve complained about their conditions,” he said. “Regardless of what you’re incarcerated for . . . you need to be treated like a human, and that’s not happening here.”

An earlier version of this story incorrectly said Samsel was arrested in late March. He was arrested in January.

Peter Hermann contributed to this report.