Montgomery Proulx, 20, of Manchester, was sentenced by Judge James O’Neill to serve 10 years to life in the New Hampshire State Prison for selling a fentanyl patch to Evan Schwager, 18, of Bedford, said Hillsborough County Attorney Marguerite Wageling on Sept. 28.

Fentanyl is a powerful narcotic drug used as a pain killer. Schwager, a high school student, died as a result of the toxic effects of the drugs sold by Proulx.

Proulx also pleaded guilty to another felony charge of the sale of fentanyl and felony possession of fentanyl, and received concurrent sentences of one to three years at the New Hampshire State Prison.

The state’s investigation revealed that Proulx attended an underage drinking party at the home of Jessica Wassman of Bedford on the evening of May 9, 2008. Proulx brought fentayl patches with him that evening, selling them to individuals at the party. One of his customers was Evan Schwager.

Proulx was arrested in August 2008 on a warrant obtained by the Bedford police after an exhaustive investigation into Schwager’s death and the circumstances surrounding the underage drinking party. Proulx had been held at the Hillsborough County House of Corrections since his arrest.