Maryland's highest court overturned yesterday the death sentence of a Prince George's County man convicted of raping and robbing an Oxon Hill woman and then setting her apartment on fire, leaving the bound and gagged woman to die.

In a unanimous ruling, the Court of Appeals reversed the death penalty imposed on Donald T. Maziarz, 21, of Hillcrest Heights. The court said the judge who imposed the sentence had interpreted the state's death penalty law too harshly, and that the Circuit Court should decide again whether to sentence Maziarz to death.

Maziarz was found guilty last year of murder, rape, arson and robbery in the November 1982 death of 30-year-old Peggy Naomi Green, who had met Maziarz and a friend of his at a liquor store. Maziarz's friend, Kevin Bennett, pleaded guilty last year to the murder, rape and robbery of Green and is serving two life sentences plus 10 years.

Prince George's County Circuit Court Judge James Magruder Rea sentenced Maziarz to die in the gas chamber, saying that he had no choice in the matter despite testimony at the sentencing hearing that Maziarz was a "constant victim," neglected by his mother, and allegedly sexually abused by foster parents who practiced witchcraft.

The judge said that he was required to impose the death sentence under the state's death penalty law, which requires judges to consider a list of aggravating and mitigating factors in deciding on the sentence.

He said the aggravating factor was that the murder was committed during the course of a felony, and that the mitigating factors were Maziarz' age, and that he had "substantially impaired capacity to appreciate the criminality of his conduct," had not been convicted of any other violent crimes and was not the sole cause of Green's death.

"It would appear that unless the mitigating circumstances are overwhelming, the death penalty is mandated if any one of the aggravating circumstances is proven by the state," Rea said in a later opinion.

But the appeals court, in an opinion written by Judge Lawrence F. Rodowsky, said Rea's interpretation of the law "grossly distorts the statute to the prejudice of the accused." Rodowsky said that the court had "repeatedly said" that the death penalty should not be imposed if the mitigating factors outweigh the aggravating ones even slightly.