OKLAHOMA CITY, JUNE 10 -- The director of a research laboratory who pleaded guilty in federal court last month to falsifying chemical analysis reports involving accident investigations has resigned from the Federal Aviation Administration, an FAA official disclosed.

Dr. Delbert J. Lacefield, director of the forensic toxicology research laboratory at the Civil Aeromedical Institute, resigned effective Friday, John Clabes, FAA public affairs spokesman, told the Daily Oklahoman on Tuesday.

Clabes said Lacefield gave no reason for submitting his resignation to Dr. Audie W. Davis, acting director of the institute.

He said, however, that the resignation wasn't required in the terms of a plea agreement reached before Lacefield pleaded guilty before U.S. District Court Judge Lee West on May 26.

West has not imposed sentence but is expected to act in about a month. Lacefield could be imprisoned for 15 years and fined $30,000.

Lacefield, a 21-year veteran of the research institute, admitted falsifying three blood analysis reports in 1986. The doctor, under a contract with the Federal Railway Administration, was supposed to analyze the body fluids of train crewmen involved in accidents.

Lacefield's analyses were challenged in the investigation of the Jan. 4 collision of an Amtrak train and a Conrail train near Baltimore that killed 16 people. An investigation found nothing wrong with Lacefield's work in that crash but discovered questionable reports filed in 16 cases in 1986.

The investigation into Lacefield's activities also resulted in a suggested reorganization of the institute, an independent FAA operation at the Mike Monroney Aeronautical Center in Oklahoma City.