A District man convicted in three 1981 Capitol Hill break-ins and robberies was sentenced to life in prison yesterday, moments after a federal prosecutor described him as "so antisocial" that he should forfeit forever "another opportunity to commit another crime."

The defendant, Maurice D. Yarber, 38, listened quietly as prosecutor Mark Dubester discounted letters from prison officials describing him as a "model prisoner."

"The government's attitude is, 'so what's the big deal,' " said Dubester, who declared that the D.C. corrections system had treated Yarber far better than he had treated his victims. During the break-ins, Dubester said, some of Yarber's victims were forced to lie on the floor with a pistol held at their heads, while others were pistol-whipped or abused in other ways.

Yarber, who was arrested shortly after the April 1981 break-ins and has been in custody without bond for at least the past two years, will be eligible for parole in 18 years.

Yarber's prosecution and eventual conviction was the subject last month of an emotional newspaper account of the course of the case written by one of Yarber's victims. In an article in The Washington Post, entitled "The Eternity It Took to Convict My Robber," David Lauter described an exhausting ordeal of delays and retrials since Yarber was arrested.

Yarber was found guilty in April 1983 of 15 burglary and robbery counts in connection with the break-ins, but that verdict was set aside by the trial judge. A second trial ended in a hung jury, and in June of this year, a third jury found Yarber guilty of the 15 counts.