The 3/14 attempt rape was the most prosecutable case.

Government officials insist that while the F.B.I. has not been able to develop a prosecutable case, it has not run out of leads to pursue.

For a prosecutable case, Caverly, the D.E.A. officer, told me: "I need there to be no connection of the drug with a legitimate medical condition.

Julius Michaelson, then the State Attorney General, investigated the matter in 1977 but concluded that there was "no prosecutable case."

As long as you give them a prosecutable case, they don't want to know everything that went on out there.

Generally, veiled vague threats do not materialize into prosecutable cases.

"We came to the conclusion that based on looking at everything available at that time, there were no prosecutable cases," Mr. Dillon said.

Mr. Spota has said that the absence of prosecutable cases did not detract from the report's value.

"The DoJ devoted unprecedented resources to ferreting out polling-place fraud over five years and appears to have found not a single prosecutable case across the country," Slate reported.

"We are satisfied that there are no prosecutable cases," said Jerry Schmetterer, a spokesman for the Brooklyn district attorney.