A Dorchester man serving 10 years for armed robbery added seven years to his sentence after representing himself at trial and earning another conviction for that offense, Suffolk County District Attorney Daniel F. Conley announced.

A Suffolk Superior Court jury last week found KYON JAMES (D.O.B. 5/3/82) guilty of armed robbery, unlawful possession of a firearm, unlawful possession of ammunition, unlawfully carrying a loaded firearm, and possession of a firearm during the commission of a felony; at a subsequent bench trial, Judge Patrick Brady found him guilty of armed robbery with a firearm as a second offense.

Brady sentenced James yesterday to 15 years in state prison and two years of probation upon his release. That sentence will run concurrent with – and ultimately exceed – the prison term he is already serving following the revocation of his probation last summer for a 2001 armed robbery conviction.

Assistant District Attorney David Bradley proved that James walked into the Sunoco station on River Street in Mattapan on the evening of Oct. 6, 2007, pointed a High Point 9mm semiautomatic handgun at the clerk, and said, “Give me all the money. This is not a joke.”

When the clerk gave James a $20 bill from his pocket, the evidence showed, James went behind the counter, placed his gun in his pocket, and removed cash from the station’s register and deposit box. The clerk and robber then became engaged in a struggle.

Boston Police officers on patrol in the area observed the struggle and then saw James running across River Street while the victim yelled that James had robbed him. The officers gave chase and followed James along River Street.

A Milton Police lieutenant overheard the officers’ radio call for assistance and entered Boston to assist. That lieutenant soon encountered James in the area of 65 River St. with his hand on the butt of the firearm and the barrel in his pocket. The lieutenant ordered James to the ground, seized the gun, and recovered from his clothing an envelope with Sunoco receipts and a single $20 bill.

The responding Boston officers also identified James as the man they had seen struggling with the gas station clerk.

Following James’ indictment for the River Street armed robbery, Bradley assisted in a probation surrender hearing for the defendant in Suffolk Superior Court. At its end, James was ordered to serve eight to 10 years for violating his probation on the 2001 robbery. James had already served two and a half years for that case.

Attorney Thomas McKean acted as James’ standby counsel.