The 20-year-old son of Prince George's County's chief prosecutor was sentenced last week to an 18-month jail term with all but one day suspended after pleading guilty to breaking and entering.

Arthur A. (Buddy) Marshall III served the day in the County Detention Center last Friday. He was isolated from the other prisoners because of concern that he might be harmed by the others, many of whom were incarcerated through the efforts of his father, Prince George's State's Attorney Arthur A. Marshall Jr.

In addition, because his father is the county prosecutor, Prince George's Circuit Judge Howard S. Chasanow appointed a special prosecutor, Montgomery County lawyer James Robert Miller.

The younger Marshall, who works for the county's Public Works Department as a garbage collector, was charged with breaking into two houses in Upper Marlboro, forging and uttering (passing) a $55 check and disorderly conduct. The charges stemmed from separate incidents dating to last July.

All but the single breaking and entering charge to which Marshall pleaded guilty were dropped following plea-bargaining with special prosecutor Miller.

Miller said yesterday he was satisfied with the outcome. "I think the judge wanted him to have a look at jail," he said. "It's something that is good shock therapy for a young man."

A spokesman for the county prosecutor's office said the last time an outside attorney was appointed to prosecute a case was more than five years ago. The procedure is employed in an effort to eliminate the possibility of conflict of interest between the defense and prosecution.

Court documents show that State's Attorney Marshall originally sought to have his son's prosecution delayed until he could take tests to enter the U.S. Army. Marshall's son failed to complete the tests successfully.

Judge Chasanow also sentenced Marshall's son to 36 months of probation. The younger Marshall is one of eight children of the state's attorney.