PARIS (AP) _ A leader of the Direct Action leftist terrorist group, Regis Schleicher, was convicted Saturday of complicity in murder in the death of two policemen killed in a 1983 shootout and was sentenced to life in prison.

A second defendant, Nicolas Halfen, 24, was also convicted by the special seven-judge anti-terrorism court and sentenced to 10 years in prison.

His brother, Claude Halfen, 31, was acquitted.

A previous attempt to bring Schleicher, 30, and the Halfen brothers to trial failed last December when Schleicher threatened the jurors in a courtroom speech with ''proletarian justice.''

Five jurors withdrew over the next few days, citing health problems, forcing the judge to declare a mistrial.

Premier Jacques Chirac's conservative government then enacted a law providing for special non-jury courts of seven magistrates to hear terrorism cases.

Two policemen were shot to death May 31, 1983, in eastern Paris when they stopped a group of people carrying suspicious sacks.

After the shootout, the group of three to six men and women escaped by commandeering a passing car, according to testimony.

''I won't answer any of your questions, whatever they are,'' Schleicher said at the opening session June 3. He refused to attend later court sessions, and was not present when the verdict was read.

When the trial opened, the Halfen brothers shouted insults at the judges.

Tight security was in place throughout the trial at the historic Palais de Justice on the Ile de la Cite in central Paris. Authorities even closed two major tourist attractions in the same complex as the courthouse - the Sainte- Chapelle built by St. Louis in 1246, renowned for its stained-glass windows, and the Conciergerie, where Queen Marie Antoinette was imprisoned during the French Revolution.