A Fairfax County Circuit Court judge rejected defense motions yesterday to throw out four statements in which John C. Marteny, a self-professed drug dealer, told police he killed two Vienna-area women in their town house April 18.

Marteny's attorneys argued that police extracted the statements from their client during a six-hour interrogation May 1 that repeatedly violated his constitutional rights. Lawyer John H. McLees Jr. termed them "involuntary confessions," and said they were inadmissible because they came after Marteny indicated he might want a lawyer.

Judge Lewis F. Griffith ruled, however, that the statements could be used in Marteny's trial, scheduled to begin on Sept. 25, because Marteny "voluntarily waived his constitutional rights" and "never unequivocally asked for counsel" during the interrogation.

There was no dispute yesterday that the police gave Marteny three warnings about his rights. The only issue before Griffith was whether the statements could be used at his trial for the strangulation of Sandra D. Niccum, 22, and the beating death of Donna Tehan, 38.

Marteny, a husky, mustachioed man, testified yesterday that at the conclusion of the interrogation he said: "I killed them. I killed those girls." Marteny said that investigators later read him his rights for the third time before he dictated a 13-page statement, which he later corrected and signed. In that statement he was quoted as saying: "I murdered the girls."

At one point during the hearing yesterday, Fairfax prosecutor Robert F. Horan Jr. waved the 13-page statement at Marteny and asked: "There is no question you told them the truth in this 13 pages is there?"

"Correct," Marteny responded, his head down.

Horan called the statements crucial to his case. "If you take away these statements, we have no probable cause to arrest this man," Horan told Judge Griffith. "If you take away these statements, he's a free man, he walks the streets."

Horan said the police acted "in good faith" by reading Marteny his rights three times. Marteny twice signed forms acknowledging his waiver of those rights, according to his own testimony.

"The truth is, this defendant killed these two women," Horan said. "And the truth is, he wanted to get it off his chest."

Yesterday's dramatic hearing included more than three hours of testimony from Marteny and the playing in court of a barely audible tape recording of almost an hour of his interrogation by police.

McLees said that Marteny had "confessed in great technicolor detail to police," but argued that those statements were coerced in the more than six hours of questioning, during which he said investigators used "every psychological ploy and trick in the book."

McLees said Marteny's efforts to stop the questioning were ignored by his interrogators.

Marteny, a Falls Church resident who is being held without bond, also testified yesterday he was a regular drug user and drug dealer with a $300 a day cocaine habit, and that he had regularly purchased cocaine from Niccum.

Police testimony indicated she was killed in a dispute over cocaine, and that Tehan was killed when she unexpectedly returned home.