The two men convicted last month of the rape and murder of Stephanie Ann Roper were each indicted by a Prince George's County grand jury yesterday on more than 20 additional charges,, all in connection with the brutal slaying of the 22-year-old college senior.

If convicted of the new charges, ranging from abduction to rape and possession of a dangerous weapon, Jack Ronald Jones, 26, and Jerry Lee Beatty, 17, could be kept in prison beyond the time in which they are now eligible for parole.

Prince George's State's Attorney Arthur A. Marshall Jr. said he sought the indictments because he believed the concurrent life sentences imposed last month by judges in Baltimore and Anne Arundel counties were too lenient.

"Hopefully, they will receive two additional life sentences plus 30 years," if convicted on the new indictments, Marshall said. He added that he would seek consecutive, rather than concurrent, sentences. Both Jones and Beatty were sentenced to life terms last month, but because the sentences were imposed concurrently, they could be eligible for parole in about 12 years.

"It's our responsibility to act when we think the court is wrong," he said. "We feel that they received an inappropriate punishment . . . . Judges are not always right.

"It's not an easy case," Marshall said of the new charges, predicting that defense attorneys will make "double-jeopardy" arguments because Jones and Beatty already have been tried on related offenses.

Roper, a Frostburg State student from Croom, near Upper Marlboro, was abducted after her car was disabled on a lonely country road near Brandywine in southern Prince George's on April 3. Her burned and mutilated body was found April 11 in a swampy area in Oakville, in St. Mary's County.

Speaking before television cameras on the courthouse steps, Marshall said the new charges relate to offenses that occurred in Prince George's, while those for which the men were convicted occurred in St. Mary's.

Jones was convicted last month in a Baltimore County courtroom after Beatty testified that it was Jones who fired the shot that killed Roper. Beatty subsequently pleaded guilty to rape and murder charges in an Anne Arudel court. A huge public outcry erupted after the sentencings, and Marshall said he immediately began the investigation that led to yesterday's grand jury indictments.

Stephanie Roper's mother, Roberta Roper, said she was "pleased, obviously" with the new indictments. "Justice wasn't served the first time, so I think this was due." She said she hoped the new charges would result in "suitable punishment for the crimes, because that's not what happened the first time."

Marshall said Vincent Roper, the victim's father, contacted him after the sentencings last month to ask if further charges would be brought, but the prosecutor added that the Roper family "has not asked for anything." He said he first looked at the possibility of bringing charges against the two men last April, but decided to wait until St. Mary's prosecutors finished their case.

On Tuesday, members of the Stephanie Roper Committee, set up by friends of the Roper family, rallied at the State House in Annapolis as they prefiled legislation that could greatly increase punishments for those found guilty of violent crimes.

Marshall said his office received more than 400 letters and phone calls protesting the Jones and Beatty sentences. He said he forwarded the letters, names and comments to Victor Pietkiewicz, chairman of the committee, along with a letter promising that both he and his staff "all fully and completely support your efforts and are available to assist you in any way possible."

Pietkiewicz said yesterday the committee also is pleased with the new indictments. "When the trial comes up you will see the courtroom full every day," he said. "No matter where it is -- Eastern Shore or Western Maryland -- we will be there."

Last Friday, a grand jury in Charles County indicted Jones on charges -- unrelated to the Roper slaying -- of possessing and distributing a derivative of the drug PCP last February. State's attorney Stephen J. Braun said he decided to ask for the indictment because he, like Marshall, believed the sentence Jones received was too lenient.