Most of the persons who died during the worst rash of heroin overdoses in the District also used alcohol prior to their deaths, the D.C. medical examiner's office said yesterday.

While none of the alcohol levels in the victims was considered lethal, alcohol and heroin taken together can result in death because both drugs are depressants, according to Philip Santinga, a toxicologist in the department.

"When you mix alcohol and another depressant together, it has an additive effect," Santinga said. "A person who drinks could take a lower than lethal dosage of heroin and still overdose."

During the first four days of March, eight persons died in the city from heroin overdoses and one person died in Prince George's County.

D.C. police believe that all nine victims bought street heroin marketed as "J.R." in far Southeast.

No arrests have been made in the case, police said.

Santinga said that while other factors can contribute to overdoses, toxicologists consider a lethal dose of heroin to range between 0.01 milligram percent and 0.30 mg percent in the blood.

The eight people tested in the District showed levels from 0.03 mg percent to 0.20 mg percent, he said.

Tests results on the Prince George's victim were not available.

Santinga said in addition to alcohol, the speed at which the heroin is injected, the purity level of the heroin and other drugs used by the victims can cause overdoses.

"There have been cases where two people will split a quantity of heroin and one will inject it slowly and one will inject it quickly," he said.

"The one who injected it quickly died. The one who did it slowly lived."

"We had 140 heroin deaths last year [in the District] and no one paid much attention when they were spread out over the year," Santinga said.

"The number of deaths and the grouping says there was some strong heroin out there on the streets."