A Bethesda psychiatrist testified yesterday in Montgomery County Circuit Court that two alter-personalities of a convicted killer -- a demonic dog and a devil worshipper -- were responsible for the April 1989 slaying of a 24-year-old woman and the attempted murder of her lover.

"I know with a 99 percent probability who shot the victim," Richard S. Epstein told a jury yesterday at the trial of Michael D. Proctor, a former medical student at Howard University.

"Clarence and Tufu in concert fired the gun," Epstein said. "Tufu was the hatchet man for Clarence."

According to Epstein, Clarence, a Satan follower, and Tufu, a Pekingese dog with demonic eyes who demanded blood sacrifices, were two of six personalities of Proctor, 28, of Silver Spring.

Epstein, during five hours of testimony yesterday, said he had seen each of the personalities during 25 hours of interviews with Proctor over 10 months.

Along with Clarence and Tufu, Epstein said the other personalities were "Abdul," a Muslim; "Rick," a light-hearted teenager who loved to race cars; "Vic," a 25-year-old man who enjoys cooking; and "Thriller," a personality who emerged in 1982 while Proctor was pledging a fraternity at a Mississippi university.

Epstein was the key defense witness during the insanity phase of Proctor's trial. On Monday, the jury found Proctor guilty of first-degree murder in the shooting death of Sandra Wright and attempted first-degree murder of Johnny Dinkins, 27. He faces two life terms in prison for the convictions.

Defense attorney Alan C. Drew said Proctor was not criminally responsible for the slaying and attempted murder because he suffers from multiple personality disorder. If the jury believes Proctor was mentally deficient at the time of the shooting, he would be committed to a state mental hospital for treatment.

Prosecutor John McCarthy attacked Epstein's diagnosis of Proctor's multiple personality disorder, saying the defendant feigned the illness to escape punishment.

But Epstein staunchly defended his claims, saying Proctor began developing the alter personalities at age 10 to cope with an abusive stepfather and the death of a grandmother.

Epstein said the most dominant alter personality was Clarence, an aggressive, "wild-looking" man who told Epstein during one interview, "Michael is dying. I'm draining him of his energy. I worship the devil."

The most frightening personality was the demon-like dog, Tufu, said Epstein. Tufu had "blaring, hate-filled eyes. I didn't want to be alone with him. I felt he was the murderer."

On cross-examination yesterday, McCarthy asked Epstein if he could show the jurors Tufu's "demonic eyes" in a color videotape of a 90-minute interview on Nov. 9 with Proctor.

"There it is," Epstein shouted as the tape showed a picture of the defendant in a prison uniform. "Look at that. It's a real dirty look," Epstein said, as the defendant grimaced and raised his eyebrows.

Several jurors shook their heads and smiled as spectators and lawyers gathered around the television set. Proctor remained at the defense table, his head resting on the palm of his hand.

After several minutes, McCarthy asked Epstein, "Was that our murderer we just saw on the videotape?" Responded Epstein, "That was the eyes of the murderer I saw and sat with."