AUBURN — One of three men charged with robbing a Lewiston man of his medical marijuana pleaded guilty Wednesday to related charges.

Derrick J. McDuffy, 22, pleaded guilty in Androscoggin County Superior Court to robbery and burglary in connection with the September 2011 incident. For those charges, he agreed to a sentence of 10 years in prison, all suspended except for three years. He also agreed to three years of probation following his release.

McDuffy also pleaded guilty to violation of conditions of release and to theft by unauthorized taking, and agreed to a sentence of six months in jail, to be served at the same time as his three years in prison.

On a charge of criminal threatening, he pleaded guilty and agreed to a one-year prison sentence, also to be served during his three-year sentence on the robbery and burglary charges.

In addition, McDuffy pleaded guilty Wednesday to a felony trafficking in prison contraband charge stemming from an April violation involving Suboxone, a drug used to treat opiate addiction. For that, he’ll serve a six-month sentence concurrent with the other sentences.

McDuffy had been scheduled for trial later this month.

Earlier this year, co-defendant Ricardo Hairston, 20, of Lewiston, a former Edward Little High School track star, pleaded guilty to charges stemming from the robbery. He was sentenced to 10 years in prison, all suspended except for two years, plus three years of probation.

Kevin Stitchel, 22, pleaded guilty to charges of robbery and criminal threatening with a dangerous weapon. He was sentenced to 10 years in prison, with six years suspended, plus three years of probation.

The three men were arrested and charged in the September 2011 robbery of Scott and Wendy Breton at their Pierce Street apartment.

Scott Breton said the men, whom he didn’t know, had come for his marijuana, which he said he used legally for health problems. One of the men put a shotgun against Breton’s face and threatened repeatedly to shoot him, he said.

One of the men was armed with a double-barreled shotgun and another with a handgun when they kicked in the Bretons’ door at about 9 a.m., he and his wife told police.

The couple said the men knew Scott Breton had marijuana. The couple also was robbed of an iPod, a cellphone and a laptop computer.

Wanda Breton called police from her cellphone. Within minutes, police arrived.

Although Scott Breton didn’t recognize the men, he was able to describe them. Police tracked the three to an apartment building around the corner at 21 Walnut St. At that address, police found the two guns and some of the stolen property that had been stuffed into a dryer. They said they found the suspects hiding in another apartment on the third floor.

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