A former Newport man was sentenced Tuesday in U.S. District Court in New Haven, Conn., to 20 years in prison for possessing child pornography — the maximum sentence allowed.

Richard C. Poupart, 53, of Middlefield, Conn., faced enhanced penalties because of a previous conviction for sexual assault of a minor, according to the U.S. attorney’s office in Connecticut.

In addition to prison time, U.S. District Judge Janet Bond Atherton sentenced Poupart to a lifetime of supervised release after he completes his prison term, according to a news release issued by David B. Fein, U.S. attorney for Connecticut.

“This defendant has a history of sexually assaulting minors, and this significant sentence will protect children from future harm,” Fein said.

Poupart has been held without bail since Aug. 6, 2010, according to court documents. He pleaded guilty to one count of possession of child pornography in May 2012 in federal court in New Haven, Conn.

Police in Connecticut seized Poupart’s computer in 2007 after allegations that he had sexually assaulted two minor female relatives, according to court documents. Subsequent forensic examination of the seized items revealed images and videos of child pornography, including images that Poupart took of one of the minor female relatives in 2003.

Poupart’s attorney, C. Thomas Furniss of Hartford, Conn., argued in his sentencing memorandum that his client should receive the mandatory minimum sentence of 10 years in prison. The lawyer said that Poupart agreed to plead guilty in hopes of a lower sentence than one he might have received had he gone to trial.

“From the beginning, [Poupart] claimed that he was innocent of this crime and did not view or transport child pornography,” Furniss wrote. “Mr. Poupart maintained that he worked as a computer repair technician and must have acquired these images, if at all, from customers while performing data recovery on their computers.”

Poupart received the maximum sentence, in part, due to his criminal history, according to the U.S. attorney’s office.

In June 1991, Poupart was convicted in Vermont state court for sexually assaulting a 14-year-old girl. In July 2009 in Connecticut, he was convicted of two counts of fourth-degree sexual assault against minor female relatives, according to court documents.

Poupart was living with his mother in Newport before moving to Connecticut, federal prosecutors stated in their sentencing memorandum that asked the maximum 20-year sentence be imposed. Court records stated that in 2003 or 2004, two minor female relatives visited Poupart in Maine, where he abused them and attempted to get one of the girls to play strip poker with him.

While he does not appear to have been prosecuted in Maine, Poupart was convicted in August 2009 for sexually assaulting the same girls in Connecticut in 2006 and 2007. He was sentenced to one year in prison, according to the U.S. attorney’s office. The federal charge was lodged shortly before he was to be released from state prison.

Poupart was convicted of failing to register as a sex offender in Vermont and also failed to do so in Connecticut, according to the court documents. He was listed on the Maine registry when he lived in Newport, according to the records.

Poupart faced a minimum mandatory prison term of 10 years and a maximum of 20 years with a fine of up to $250,000.