An Anne Arundel County jury got a glimpse at life in one of the state's roughest prisons in the death penalty trial of one convicted killer accused in the stabbing death of another convicted killer.

"It wasn't much of a fight. It was an ambush, a jumping, if you will," Assistant State's Attorney Frederick M. Paone told the 12 jurors and six alternates in opening statements yesterday morning in the murder trial of John Ashby, 30.

Ashby is charged in the death of Damon Campbell, 28, who died Feb. 13, 2000, of complications from head wounds nearly two months earlier in the Maryland House of Correction Annex in Jessup.

Paone told jurors that Ashby attacked Campbell from behind Dec. 17, 1999, slashing his head with a homemade knife - revenge for a previous assault by Campbell. Retaliation - whether in an upper-class neighborhood or in prison - is against the law, he said.

But Ashby's public defender, Keith J. Gross, told jurors that the crime goes back to July 19, 1999, when Campbell attacked Ashby. He presented Ashby as the victim of a failed prison system who received no protection from officials and whose life was threatened again by Campbell. He said Ashby acted in self-defense.

Gross asked jurors to imagine being knifed and then learning that the person who did it "is still out there, walking around freely, able to attack you again. ... You would have to do whatever it is to protect yourself."

Ashby is serving a life sentence for a killing in Prince George's County; Campbell was serving 90 years for murder and related convictions in Harford County.

The case is unusual because prosecutors are seeking the death penalty against Ashby, an indication they feel they have a strong case. None of the prisoners on Maryland's death row is convicted of a prison murder. Local and state public safety officials said they do not remember a prison murder trial that ended in a death sentence. But any first-degree murder that occurs in prison is automatically eligible for consideration for the death penalty.

The trial opens a little more than a month after Gov. Parris N. Glendening declared a moratorium on executions while a study examines the fairness of how the death sentence has been applied.

If the jury convicts Ashby of first-degree murder, jurors would consider the sentence in a second phase of the trial.

The trial, before Circuit Judge Ronald A. Silkworth, is expected to continue all week.