A 29-year-old Northwest woman has been arrested and charged with involuntary manslaughter in a woman's death from a heroin overdose in May.

Sandra M. Wills was accused in D.C. Superior Court yesterday of twice injecting Joanne Stewart with heroin. Stewart later died in a hospital emergency room of a drug overdose.

U.S. Attorney Joseph diGenova said that while it is unusual to bring charges in a drug overdose death, the case was "part of a continuing effort to deal with all aspects of this serious [drug] problem." DiGenova added that an investigation was continuing into bringing possible charges against those responsible for a string of deaths caused last winter by a particularly potent form of heroin.

DiGenova pledged in March that those who sold that batch of heroin would be charged with the deaths that resulted from its use. At that time, legal experts said charging those who sell or administer drugs with murder was a seldom tested legal principle. They added that it would be extremely difficult to prove someone knew a drug would result in a death.

Prosecutors said they know of only one other recent instance in which someone has been charged in connection with a drug overdose death.

Two years ago a Washington drug dealer pleaded guilty to manslaughter in the death of a man who had purchased extremely powerful heroin from the dealer.

According to an affidavit filed in support of the arrest warrant, Wills bought a syringe and some heroin on May 4, and she and Stewart then returned to Wills' Northwest apartment.

Wills, described as having been a drug addict for 10 years, allegedly "cooked up the heroin and hit Joanne twice in the right arm," the affidavit said.

Stewart, who lived at 1309 Columbia Rd. NW, became unconscious and was taken by ambulance to Howard University Hospital where she died in the emergency room. A medical examiner said that the cause of death was a heroin overdose.

Prosecutors said yesterday they decided to press charges against Wills because of the "strength of the evidence."

According to the affidavit, Wills, of 811 R St. NW, told police she had injected Stewart. Wills was released yesterday on her own recognizance.

A source in the U.S. attorney's office said yesterday that there was some debate among prosecutors as to whether Wills "was only doing what the victim wanted" when she injected Stewart. The source added that such an argument could be a sympathetic defense.

Despite such discussions, the source said it was a "straightforward decision to prosecute." This source explained that it was the policy of the U.S. attorney's office to send all homicides that "we can prove" to the grand jury regardless of whether the defendant may appear to have a sympathetic case.

One of the most celebrated incidents of bringing murder charges against someone connected with a drug overdose death occurred when Cathy Evelyn Smith was accused of injecting comedian John Belushi with a fatal combination of cocaine and heroin on March 5, 1982. She is awaiting trial in Los Angeles.