A Bronx, N.Y., woman pleaded guilty yesterday to giving police a false statement about the 1986 slayings of a suspected Prince George's County cocaine dealer and his daughter.

In return for the plea, prosecutors dropped charges of accessory to commit murder after the fact and obstruction of justice charged against Ann Marie Spence, 27. Spence, a former girlfriend of the man, first told police she knew nothing about the deaths, then said she poisoned the victims by putting oven cleaner and cocaine in their chicken.

An autopsy, confirmed by an Armed Forces Institute analysis, found no such corrosive chemicals in the food eaten by Dennis and Donna White, whose bodies were discovered at White's Temple Hills home May 5, 1986.

Spence, who has no prior criminal record, is to receive a $500 fine and probation under the agreement worked out with Circuit Judge Darlene Perry and announced in the courtroom yesterday by prosecutor Joseph B. Chazen.

Charges were previously dropped against three persons who were charged in the slaying. One person, Gene Patrick Clark, still faces trial, on Jan. 18, in the case.

Shortly after the slayings, police found $1 million in cash thought to be profits from illegal drug sales stashed in a suitcase in the attic of the Whites' home.