os Angeles County Coroner Thomas T. Noguchi announced tonight that actor John Belushi's death Friday was caused by an overdose of heroin and cocaine injected into his bloodstream.

The coroner's statement said: "The deceased died from an overdose due to intravenous injection of heroin and cocaine. Both cocaine and heroin were found on the premises." Noguchi's secretary said the coroner would comment on the toxological test results Thursday.

But an ear, nose and throat specialist who had treated Belushi, and who asked not to be named, said Belushi was allergic to Novocain and possibly to related drugs such as cocaine.

He said Belushi had been warned against using them. The use of such drugs would increase the possibility of respiratory failure if Belushi had taken cocaine, the doctor said.

The coroner's announcement came after days of unconfirmed reports of drug involvement in Belushi's death, as the beleaguered coroner appeared to try to hold off an announcement until final tests had been made and dampen his reputation for damaging off-the-cuff remarks after celebrity deaths.

Police Chief Daryl Gates called the death a "useless loss," as he confirmed for reporters today reports that needle marks had been found on Belushi's arm.

He said there was no evidence someone else gave Belushi the fatal injection of the two drugs--known as "hardballing." He said he expects no charges to be filed in the case.

The Associated Press reported that Gates also identified a woman who apparently was the last person to see Belushi alive, giving her name as Evelyn Smith. She was not further identified.

Hollywood Division homicide detective Russell Kuster had said earlier that the woman was "in the entertainment industry."

According to police spokesman Lt. Dan Cooke, the woman told detectives that Belushi awoke about 8 a.m. with breathing difficulties on the day he died.

Cooke said that Belushi told the woman he was suffering from nasal congestion. She told detectives she gave him a glass of water, then left him alone in the bedroom while she had breakfast and then went out. Belushi died while she was gone.

The actor and comedian died in a $200-a-day bungalow at the fashionable Chateau Marmont Hotel in Hollywood. He had reportedly been out all night the evening before with friends at the Roxy nightclub on Sunset Strip and ate at a nearby restaurant, but later vomited.

The initial reports of the death had suggested some respiratory failure since Smith, who was with Belushi Friday morning, said he had complained of breathing difficulty. Toxicologists say cocaine can constrict the lungs and cause breathing problems.

Noguchi came under fire for off-the-cuff statements made after the deaths of movie stars William Holden and Natalie Wood. His office appeared to have failed to detect the presence of the drug PCP in the tissues of a Long Beach football star who allegedly committed suicide after being arrested for a traffic violation. A highly critical audit of the coroner's department released Monday blamed Noguchi for a series of management problems and was critical of his supplementing his $69,341 annual income with outside lectures, teaching and consulting work.

Some county supervisors are known to favor firing Noguchi, who was reinstated in 1969 after a similar board effort to dismiss him. He is protected by an old civil service rule which requires he be dismissed only for "good cause." And he has threatened to take immediate legal action, as he did in 1969, if fired again.