Federal Drug Administration tests on candy believed to be poisoned with strychnine were unable to identify the substance, and the agency is still investigating, an agency spokesman said Saturday.

A powder was found on a piece of candy in a package of Sunkist Fun Fruits and Dinosaurs bought at a northern New Jersey grocery store. Bergen County prosecutor Larry McClure said Friday that state police laboratory tests had determined the powder was strychnine.But FDA spokesman Edward Wilkens said the agency's lab in Brooklyn, N.Y., was unable to confirm the powder was strychnine. He said only a small piece of the candy in question was available for testing, and officials were trying to determine why the results from the two labs differed.