The conductor of a Conrail train that collided with another freight train near Lewistown, Pa., Jan. 14, killing four crew members, used marijuana before the accident, officials said yesterday.

A report issued by the Federal Railroad Administration said "samples provided by the conductor of the eastbound train tested positive for marijuana metabolite in the urine."

Bill Loftus, executive director of the FRA, said the Transportation Department agency is not drawing any conclusions whether the suspected marijuana use might have played a role in the collision.

"It is up to the National Transportation Safety Board to investigate the accident and determine the probable cause," he said. Loftus declined to identify the conductor or to comment about how much and when the marijuana is suspected to have been used.

Freight trains are run by engineers, but conductors watch signals and can take emergency action.

The rest of the crew tested negative for drugs.

"Available samples for the front brakeman of the eastbound train were very limited, due to the severity of the crash and ensuing fire," the FRA said.

"Tests of those specimens did not indicate use of alcohol or drugs," it said. "Alcohol was present at low levels in the tissue samples, but FRA is advised that it was very likely present as the product of post-mortem microbial generation."