ST. PAUL, Minn. - The St. Louis County medical examiner clarified yesterday that although he listed the cause of death for the pilots and passengers in Sen. Paul Wellstone's plane as injuries from the crash, he still is conducting tests to see whether the fire affected the passengers before they died.

Dr. Thomas Uncini, St. Louis County's chief medical examiner, said there are still some microscopic tests he can do on tissue and other samples from Wellstone and his fellow passengers. In addition, he has asked for their tissue samples to be returned from the Federal Aviation Administration laboratory in Oklahoma City.

That lab was unable to do tests to look for carbon monoxide in the tissue samples, Uncini said. Another lab said it could do that work; Uncini said he will turn the samples over to it.

Uncini said there is no question that the pilot, Capt. Richard Conry, and co-pilot Michael Guess died from injuries suffered in the crash. Blood samples showed no carbon monoxide in the blood, indicating they were dead before the fire broke out in the plane.

However, the passengers were farther back in the plane and closer to where the fire probably originated, so he wants to determine, if possible, whether the sequence of events was the same for them. The difficulty is that the fire affected the passengers more than the pilots, leaving no blood to test, Uncini said.

Uncini has concluded that neither pilot suffered a medical problem such as a stroke or a heart attack.