David Bertowitz, attorneys entered innocent pleas today to murder and assault charges against the man accused of being "Son of Sam" and served notice they would use a defense of insanity if the case goes to trial.

he 24-year-old defendant, protected on three-sides of his chair, by a human shield of eight court officers, spoke publicly only to give brief answers to questions from the clerk during the arraignment in state Supreme Court.

His hands manacled, Bertowitz, dressed in blue jeans and a blue-and-white stripped shirt with an American flag pin, appeared alert conferring with his lawyers. The slight smile that characterized his expression last week after he was arrested was gone.

After the brief proceeding, Berkowitz was returned to Kings County Hospital in Brooklyb where he is undergoing mental tests to determine whether he is capable of standing trial.

Justice Leonard Yoswein said he expected to receive the results of those thests by Aug. 30.

Meanwhile, a 40-page a loose-leaf dairy reportedly a detailed account of the "son of Sam" slayings providing was found in Berkowitz's apartmen, police said.

In another development, the New York Post quoted workers at Kings County Hospital as saying the suspect told them he wished he were on the streets stalking victims instead of pacing in a cell.

"I should be out hunting tonight," Berkowitz was quoted by the Post as telling the workers, who are not identified.

The reputed record of the "Son of Sam" slayings was found in Berkowitz's Yonkers apartment strewn about the floor among pornographic literature and newspaper clippings of the crimes, the police sources said.

The sources said the diary provides an "encyclopedic" account of the attacks, a description of the victims, practicles followed by "Son of Sam" to avoid arrest and mistakes by police in the case.

According to the diary, "Son of Sam," contrary to earlier police theory, would linger in the area of his nighttime ambushes rather than make speedy getaways along expressways. Police said the diary related how "Son of Sam" often would stop at all-night diners for something to eat after his attacks.

The Post also reported today that Berkowitz' attorneys had located his natural mother, who gave him up for adoption at birth, and quoted a source as saying she had seen him only once since - at an "unhappy" reunion three years ago.

The newspaper said the meeting sourced because Berkowitz found out that his mother had also given birth to a daughter but had not put her up for adoption.

At the arraignment, Yoswein put off until Aug. 30 any action on lawyer Philip Peltz' move to withdraw from the case. But he ordered tape recordings that Peltz made with Berkowitz - and reportedly tried to sell - turned over to the court for safekeeping.

The arraignment was on charge returned by a grand jury Monday, accusing Berkowitz of killing Stacy Moskowitz and attempting to kill Robert Violante, both 20, on July 31. Berkowitz has not yet been charged with any of the five other killings attributed to the gunman who called himself "Son of Sam."

Stringent security was in effect in the courthouse. Reporters and spectators had to pass through two metal-detecting gates to enter the seventh floor courtroom, which has scats to space.

A crowd of up to 400 booed as the green van believed to be carrying Berkowitz left the courthouse later. But there were no incidents, and the van sped off with its escort of four police cars filled with shotgun-toting officers.

Meanwhile, the parents of Moskowitz today notified the City of Yonkers that they intend to sue if for $10 million, charging negligence in that the suspect was not arrested sooner.

Their attorney, Spencer Lader, said the notification was a formality and did not rule out that other parties would be named in the suit, to be filed shortly in state Supreme Court.

Among the leads that should have led to immediate investigations of Berkowitz, Lader said,. were complaints by a Berkowitz neighbor, Sam Carr, that his dog has been wounded by a bullet found to be .44 caliber.

"Had Yonkers police done their job, I think Berkowitz would have been in jail" before July 31, the morning Moscowitz was killed, he said.