(CNN) Anthony Weiner, the former politician and now convicted federal sex offender, reported Monday morning to Federal Medical Center Devens, a federal prison in Ayer, Massachusetts. He will begin serving his 21 months for sexting with a minor.

According to the institution, FMC Devens is one of six federal medical centers in the country. Dzhokhar Tsarnaev, the surviving brother in the Boston bombing attack, was also originally held at FMC Devens.

While some federal inmates are transferred to Devens from other prisons when serious medical treatment is needed, Weiner was ordered to serve his term at Devons from the beginning.

In May, Weiner, 53, pleaded guilty to one charge of transferring obscene material to a minor in federal court in Manhattan. The charges stem from communications that the former congressman had with a 15-year-old girl on social media sites between January and March 2016. At his sentencing in September, Judge Denise Cote of the Southern District of New York added that at the time Weiner was communicating with the girl, he was "in contact with 19 other women."

According to a document from the Department of Justice, sex offenders make up approximately 40% of the inmate population at FMC Devens. The prison offers a sex offender treatment program described as a "voluntary, intensive, residential therapeutic program for higher risk male sex offenders."

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