The executive director of the Prince George's County Human Relations Commission has found probable cause to believe that "excessive force" was used in the 1975 fatal shooting of a Palmer Park youth by a county policeman.

The death of 18-year-old Michael A. Washington on April 30, 1975, climaxed a bizarre, 24-hour period during which police attempted to serve several warrants on him, shot and killed his family's pet dog, and later warned his parents that he might be shot if he did not turn himself into police.

The shots that killed Washington who was hiding in a closet at the time, were fired by Pfc. Frank Cohee, then 24, who was responding with another officer to a report of a break-in at 7441 79th Ave., Palmer Park, according to a police spokesman. Cohee had been involved in the shooting of the pet dog during an earlier attempt to serve a warrant on Washington, the spokesman said.

Cohee was routinely placed on administrative leave with pay by the county police department, which later cleared him of any wrongdoing in the incident. The staff of the Human Relations Commission undertook its own probe, resulting in the director's finding earlier this year, one commissioner said yesterday.

A commission panel, under procedures spelled out by county regulation and executive order, was scheduled to hold its second closed-door hearing on the matter last night. A first hearing was held June 30.

Josephine Campbell, panel chairperson said yesterday, "After we find whatever we can, we either recommend (to the full commission) dismissing the matter or urging the county executive to convene a (police) trial board."

A trial board could suspend or dismiss the policeman or take no action.