An Israeli court's decision to delay the arraignment of Montgomery County murder suspect Samuel Sheinbein for a second time prompted Montgomery's chief prosecutor yesterday to accuse the Israelis of not taking the case seriously enough.

Montgomery State's Attorney Douglas Gansler (D) said he is frustrated by Israeli prosecutor Hadassah Naor's agreement to another delay sought by Sheinbein's lawyer, David Libai. Gansler said Naor has told Montgomery prosecutors that "she hasn't really focused on the case. . . . It's not been at the top of her pile."

"Right now [the case] is in limbo, which is frustrating because they're the ones who decided not to send him back," Gansler said. "You'd like [Israeli prosecutors] and the Israeli judicial system to take it seriously, but so far, we can't even get the arraignment done."

At the arraignment, Sheinbein, 18, must answer the charge against him -- premeditated murder with intent to kill, Israel's equivalent of first-degree murder -- in the slaying and dismemberment of Wheaton teenager Alfredo Enrique Tello Jr., 19, in September 1997.

The hearing, originally scheduled for May 16, was delayed again yesterday at the request of Libai, who told the court he needed more time to prepare. Libai, a former Israeli justice minister, is an adviser to Ehud Barak, who was elected prime minister by a landslide in May but who has not yet forged a coalition government.

Sheinbein fled to Israel three days after Tello's charred and mutilated torso was found in the garage of a vacant Aspen Hill home.

Sheinbein claimed Israeli citizenship through his father, who was born in British-ruled Palestine. He successfully fought extradition to the United States during a 17-month court battle that strained U.S.-Israeli relations.

Gansler said Sheinbein's trial, tentatively set to begin in September, probably will be delayed. The teenager's lawyer has suggested that Sheinbein would plead guilty and that he also would push for a lighter sentence for his client by arguing that he had "diminished mental capacity" at the time of the crime.

If convicted, Sheinbein would face up to life in prison, though legal experts have said such sentences usually are cut to 20 years in Israel.

Sheinbein's lawyer could not be reached for comment. The teenager's co-defendant, Aaron Needle, hanged himself in his Montgomery jail cell in April 1998 on the eve of his trial.

CAPTION: Samuel Sheinbein consulted with lawyer David Libai at November court hearing in Jerusalem. Sheinbein is charged in the slaying of a Montgomery County teenager.