A Maryland Penitentiary inmate facing a possible death sentence for fatally stabbing a prison guard said today he felt "no threat to my life from the state" because he was confident that jurors could see through "garbage" testimony against him by a "long procession of liars."

During an often contentious day of cross-examination, Nathaniel Appleby, a 25-year-old convicted murderer, stood by his testimony that he acted in self-defense after guards beat him.

Prosecutors have said that they will seek the death penalty if Appleby is convicted of murdering guard Herman Toulson, 39, on Oct. 6 in the South Wing of the penitentiary here.

Appleby, who said today he was "surprised" that Toulson died from his wounds, is also charged with the attempted murder of guard Willie J. Newkirk. Newkirk testified earlier that Appleby stabbed Toulson without provocation.

The prosecution's case has been clouded by testimony from prison guards that they saw Appleby beaten after the incident and that they omitted that fact from their reports, attributing Appleby's injuries instead to a fall. Appleby was hospitalized for a broken arm and injuries that required 108 stitches after the incident.

Appleby told prosecutors Donald J. Giblin and Kurt L. Schmoke that they had been "humiliated" by prison guards who lied to them, and that they were only continuing with the trial because "it's a reputation thing on your part now."

But Giblin, responding to Appleby's contention that guards had "committed outright perjury" on the witness stand, questioned Appleby's own motivations to lie.

"If a guard would lie to protect his job, wouldn't an inmate lie to protect his life?" Giblin asked. "Wouldn't you lie to save your life."

Appleby responded, "I don't feel no threat to my life from the state . . . because I know I'm in the right, and truth will prevail. I have 12 people here that's listening to the boys you put on the stand and I have no doubt they can see through that garbage."

Appleby said, however, that it was "possible" he lied to a social worker, in order to gain admittance to Patuxent Institution, the prison system's mental hospital, so he could get out of the penitentiary.

He also admitted selling drugs to inmates and to attacking them, at times without provocation.

But Appleby stood steadfastly by his testimony yesterday that Toulson, Newkirk and several other guards surrounded him and beat him when he was out of his cell during an exercise period. He said they were acting in retaliation for an earlier incident in which guards had charged that Appleby prevented them from subduing another inmate armed with a knife.

Speaking after court today, Giblin declined to comment on Appleby's charges that prosecutors were only proceeding with the case as a matter of "pride."

"I'm just trying to do my job," Giblin said.

Cross-examination is to conclude tomorrow, and the jury is expected to get the case later this week.