Arthur A. (Bud) Marshall, the state's attorney for Prince George's County, will begin considering today whether to present to a grand jury the case of Peter F. Morgan, a county policeman who fatally shot an unarmed, fleeing shoplifting suspect last week.

Marshall said he will review a report on the shooting of 32-year-old William Ray compiled by the police department's homicide squad before deciding whether to go to the county grand jury and seek an indictment of Morgan.

However yesterday, before he had seen the homicide report, Marshall indicated that a presentment to the grand jury was likely. "From everything I've seen and heard," Marshall said, "it seems to me to be a very simple set of circumstances."

According to police reports on the incident, Officer Morgan shot Ray in the back of the head at 2 p.m. Christmas Eve, some two days after Ray had been picked up for allegedly shoplifting two $7 hams from a Giant Food store in Coral Hills. Ray had broken free from Morgan while being booked at the district police station in Seat Pleasant. The shooting followed a brief chase from the police station to a churchyard, where Morgan ordered Ray to half, then fired the fatal shot.

Since the shooting, there has been some controversy as to whether Ray - who was found to have two hypodermic needles in his pocket - was a heroin addict or a diabetic and whether, at the time of the shooting, he was a misdemeanant or a felon.

Marshall said that while those questions may have some bearing on the outcome of an administrative review of the incident by the police department, they "have absolutely nothing to do with" the criminal aspects of the case.

"Police regulations have no bearing," said Marshall. "Maryland case law has bearing." The case law Marshall will rely on states that it is better to allow a known misdemeanor to escape as long as the crime was not a violent one.

Officer Morgan has been placed on administrative leave suspended with pay - since the day of the shooting. Ray's family - his mother, Ella, two brothers and sister - have charged that the shooting was, in the words of brother David, "part of a pattern of brutality by police officers in Prince George's against black people. Morgan is white: Ray was black.

An autopsy conducted yesterday by Deputy State Medical Examiner Bert Morton did not determine whether Ray was a diabetic or a drug addict. It did show, according to Dr. Morton, that he did not inject narcotics into his veins.