By CLIFFORD KRAUSS

The New York City Medical Examiner's office said yesterday that a Staten Island man who died in the custody of police officers 10 days ago suffocated because of pressure on his chest and neck while he lay in a prone position with his hands handcuffed behind his back.

The Chief Medical Examiner, Dr. Charles S. Hirsch, called the death a homicide because, he said, it was caused at least in part by the action of the officers, who were members of an anti-narcotics squad who had gone to a low-income housing complex on northern Staten Island to make drug arrests.

Whether the officers' actions constituted a crime, or were a justified use of force to restrain a suspect, must now be weighed by a grand jury under the direction of the borough's District Attorney, William L. Murphy.

A lawyer for the family of the dead man, Ernest Sayon, 22, predicted that no Staten Island grand jury would indict a police officer for assaulting a suspect, especially one who is black, and he promised to push for a Federal civil rights investigation. Of the three officers who the Police Department has said were involved in the arrest of Mr. Sayon, and who have been placed on desk duty since the incident, one is black.

City officials responded cautiously to the Medical Examiner's conclusion. "At this point," Mayor Rudolph W. Giuliani said, "we really should be patient and await the outcome of the grand jury investigation."

Mr. Giuliani later went to Staten Island, where he was loudly heckled by demonstrators when he addressed them outside Borough Hall. He also met with a small contingent of demonstrators.

Police Commissioner William J. Bratton said the report did not necessarily imply criminal behavior on the part of the three officers, although he promised to review department procedures in restraining prisoners. "I'm not going to draw any conclusions at this juncture," he said.

Police officers are given broad discretion to use "necessary force" to overcome suspects who are resisting or posing a threat to the police or the public. But since November 1993, officers have been banned from using choke holds, which cut off the flow of oxygen and blood to the brain. The policy also says that "whenever possible," officers should not use other restraints like sitting or standing on a suspect's chest.

James Lysaght, a lawyer for the Patrolmen's Benevolent Association, the police union, said there was no evidence that the officers used a choke hold on Mr. Sayon. The officers' actions "in this case," he said, "were consistent with proper police action under the circumstances and were in no way criminal."

The District Attorney said he was not yet ready to recommend to a grand jury that the three police officers be charged with murder until he interviews several more witnesses.

Deaths of suspects in police custody have been ruled homicides before, and in some cases officers have been charged. But the only case in recent memory of a New York City police officer convicted of committing homicide while on duty was that of Thomas Ryan, who was found guilty in 1977 of beating a burglary suspect to death.

'Blunt Impacts'

In Mr. Sayon's death, a one-page statement from the Medical Examiner released yesterday said that "the cause of Mr. Sayon's death is asphyxia by compression of chest and neck while rear-handcuffed and prone on the ground immediately following a struggle in which he sustained blunt impacts to his head and trunk."

The statement said that Mr. Sayon was not under the influence of alcohol or drugs at the time of the struggle and that he had several bruises and a three-quarter-inch gash on his scalp. Ellen Borakove, a spokeswoman for the Medical Examiner, said no detailed autopsy report was issued because the case is under investigation.

Mr. Sayon was taken into custody by at least three officers of a drug enforcement team at the Park Hill Apartments, a federally subsidized private development in Clifton on Staten Island, on the evening of April 29. Several witnesses said Mr. Sayon ran from the police, was apprehended and then beaten.

His death has already touched off more than a week of sporadic demonstrations, as well as the firing of gunshots in the direction of patrolling police officers hours after the incident. The immediate reaction of Clifton residents -- many of them West African and Caribbean immigrants -- to the autopsy report yesterday was angry but muted as the police flooded the apartment complex with officers riding in vans, walking the streets and patrolling rooftops.

The Medical Examiner's conclusion comes as Mr. Bratton is seeking to navigate his department through a corruption scandal in Harlem and as the department is investigating an amateur videotape showing officers of the 120th Precinct beating another man in the Park Hill Apartments a few weeks before Mr. Sayon's death.

Commissioner Bratton said some of the same officers apparently involved in the beating were present in the vicinity of the Sayon arrest. The three officers identified by the department so far as involved in the arrest of Mr. Sayon are Sgt. John Mahoney, 35, and Officers Donald Brown, 31, and Gregg Gerson, 26.

An Undercover Squad

The fatal struggle between Mr. Sayon and the police began about 6 P.M. at Park Hill Avenue and Sobel Court after an undercover narcotics squad of eight officers attached to the 120th Precinct came to the complex. Police surveillance has increased in recent weeks in response to neighborhood demands that the city get a handle on the growing local drug problem.

The police said that while officers were arresting one man on an outstanding warrant, another man threw what sounded like an M-80 firecracker from a nearby rooftop. As the explosion flashed, Mr. Sayon ran and the officers followed him. According to initial police reports, Mr. Sayon resisted the officers and a scuffle ensued.

Mr. Sayon, a Brooklyn-born son of a Liberian immigrant family, was arrested on Oct. 21, 1992, on charges of possession of narcotics and resisting arrest. He was convicted and put on probation for three years.

On Bail in Earlier Case

Six weeks ago, while still on probation, he was arrested again on a charge of attempted murder after the police said he fired at least 16 shots from a Tech-9 semiautomatic machine pistol around the Park Hill Apartments. He was arrested and released on bail.

John Murphy Jr., the Sayon family's lawyer, predicted that the grand jury scheduled to begin deliberations on the case later this month would not move against the officers and said he would sue the city for damages on behalf of Mr. Sayon's two children.

"If the history of Staten Island is any guidance," said Mr. Murphy, a lifelong resident of the borough and son of a former Congressman, "there will be no indictment in this case. This is a white, upper-class community of egoistic hedonists."

Police officials have repeatedly said the incident should not take on racial overtones since the principal police officer involved in the case, Officer Brown, and the dead man were both black.

Copyright 1994 The New York Times Company