Army Pfc. Raymond D. Kroll, who took sanctuary in Marsh Chapel at Boston University for five days last month, was convicted Wednesday of being AWOL from his base at Fort Benning, Ga.

The court martial board at Fort Devens in Ayer, Mass., sentenced Kroll to three months of hard labor and forfeiture of $73 per month.

A higher legal authority at Fort Devens, the head of the judge advocate court, will automatically review the case, according to Kroll's lawyer, Norman S. Zalkind. "Considering precedents, there is a good possibility this review might lighten the sentence," Zalkind said.

Kroll told the court he has filed papers for a conscientious objector status. Should this appeal be accepted by a review board at Fort Devens, Zalkind explained, Kroll would either be discharged and assigned to alternative civilian duty, or assigned as a non-combatant medic in the army.

Guards barred from the fort two-thirds of the thirty members of the Marsh Chapel community who showed up to see the trial. A military spokesman cited a limited seating capacity as the reason. One would-be spectator said, "They're really uptight about us. I guess they're afraid we might actually talk to some of the other G.I.s on the base."

Kroll has been at Fort Devens since October 7 when FBI agents and Federal marshals entered Marsh Chapel and arrested him in front of 500 student sympathizers. A member of the New England Resistance, which has been in touch with Kroll since his arrest, said he has lost a lot of weight but is still "in good spirits."