Charles Turner was best friends with a "twisted psychopath," but neither that nor the fact he was a terrible witness in his own defense should be used to convict him of the robbery and murder of Catherine Fuller, Turner's attorney told a D.C. Superior Court jury yesterday.

On the final day of closing arguments that climaxed more than a month of testimony in the trial of 10 young persons accused of killing Fuller, Lloyd Elston said that Turner's friendship with Levy Rouse did not prove that Turner, too, killed the 48-year-old mother of six. The case is expected to go to the jury Monday after instructions from Judge Robert M. Scott. The 10 are charged with kidnaping, robbing and murdering Fuller in a Northeast alley and abandoned garage.

In an unusually candid assessment, Elston acknowledged that Turner, 21, also known as "Fella," had been a "terrible witness" when he took the stand in his own defense. Turner, Elston recounted, had called "his mamma a liar" when he contradicted her testimony about where Turner was on Oct. 1, 1984, the day Fuller was killed. And, Elston continued, Turner was a "stupid little chump" to be friends with Rouse, the man who prosecutors say attacked Fuller the most viciously.

But Elston asserted that the only reason Turner was sitting at the defense table was because "everyone knew he was tight with Levy."

"Everyone knew Levy was there in the garage . . . so Turner was there because he's always with Levy . . . ," said Elston.

Elston, who likened the attack on Fuller to "piranhas jumping on flesh," told the jury that it was Rouse who first dragged Turner into the case when Rouse told police that he had been with Turner on Oct. 1. Turning toward the defense table, Elston called Rouse a "twisted psychopath" who "threw a boomerang at the tablets of law" that left "blood on his pants."

Three prosecution witnesses have identified Turner as a person they saw beating and kicking Fuller. A fourth witness testified he saw Turner crossing the street with Rouse shortly before Fuller was pushed into a Northeast alley and robbed.

Turner, whose brother Christopher also is on trial, testified that he was home alone the afternoon Fuller was killed and not roaming the neighborhood as Rouse claimed in his alibi.

Elston told the jury that Charles Turner had not proved that he stayed at home that afternoon or that he was not involved in the killing. "But don't convict him . . . because he can't keep his alibi straight," said Elston.

Following the summation, Rouse stared intently at Elston. Later during a break in proceedings, Rouse whispered loudly, "You ain't got me yet, you ain't got me yet," to three detectives who had worked on the investigation. Rouse then complained to a U.S. marshal that the detectives were mocking him.

Attorney Steven Kiersh told the jury that the government had "failed miserably" in its effort to tie his client, Steven Webb, to Fuller's death. Webb, 20, has been identified by three prosecution witnesses, and Kiersh called those witnesses "liars and murderers."

During his rebuttal argument, Assistant U.S. Attorney Jerry S. Goren answered defense criticisms about government witnesses and that no physical evidence had been produced at the trial linking the 10 defendants to Fuller's death. The two key prosecution witnesses have pleaded guilty to reduced charges in Fuller's death in exchange for testifying.

"It is true that there was no physical evidence to link anyone to Mrs. Fuller's death . . . ," said Goren, holding aloft the poster-sized photographs showing Fuller's bloodied and nearly naked body in a litter-strewn garage. "But this isn't Perry Mason. This is real life."

Of the witnessess' characters and demeanor, Goren said, "who else would you expect" to have witnessed a beating as "brutal" as Fuller's and "not stop it.

"The question is not whether these are nice people, people you want to date . . . " said Goren. "The issue is truth, not trust."

In a closed courtroom session before Judge Scott, sources said a defense lawyer challenged the bias of a juror and as a result, these sources said, there may be a change Monday in the composition of the jury's 12 members.

Meanwhile yesterday, Michael Roderick Clark, 21, of 1328 Emerald St. NE, identified by D.C. police as the half-brother of defendant Webb, was arrested about 4:15 p.m. outside the courthouse at 500 Indiana Ave. NW and charged with disorderly conduct, police said. Police said the arrest came after a deputy U.S. marshal assigned to the courtroom discovered a man sleeping and ejected him from the room and then from the courthouse.

The man stood outside the courthouse for about five minutes, allegedly spitting on glass windows near the entrance, knocking over two garbage cans and and using profane language, police said.