Disgraced former congressman Anthony Weiner reported to prison on Monday to begin a 21-month federal sentence for sexting with a 15-year-old North Carolina girl and asking her to undress for him online.

Weiner pleaded guilty in May to transmitting obscene material to the girl during Skype and Snapchat conversations, and said in court that he had been a “very sick man for a very long time” but that he was undergoing treatment and it was working.

He is being held at the Federal Medical Center in Devens, Massachusetts, a Bureau of Prisons spokesperson told The Associated Press.

The facility, about 40 miles west of Boston, has more than 1,000 inmates, The AP said. More than 100 inmates are imprisoned at an adjacent minimum security satellite camp, the AP reported.

Weiner, a protégé of Sen. Chuck Schumer (D-N.Y.), had been a rising star in Democratic circles until a sexting controversy led to his resignation from Congress in 2011.

He attempted a quick comeback by running for mayor of New York City in 2013, but new sex-related allegations doomed that effort.

Weiner’s marriage to top Hillary Clinton aide Huma Abedin had once put him near the apex of political power and celebrity. Weiner and Abedin are divorcing.

His sexting with the 15-year-old last year led the FBI to reopen its probe into Clinton’s email usage while she was secretary of state.

FBI director James Comey reopened that case — an action Clinton partially blames for her loss to Republican Donald Trump — but closed the probe again just two days before the election.