"It basically shatters what some people call the best physical evidence around," chemist Pat Grant, director of the lab's highly respected Forensic Science Center told the San Jose Mercury News.

Grant and Lab metallurgist Erik Randich found that the chemical "fingerprints" used to identify which bullets the fragments came from were not quite the "smoking gun" as thought pointing to Lee Harvey Oswald as the lone gunman.

The FBI used five bullet fragments recovered from the limousine, Connally's body, the president's brain and from a stretcher for its initial tests using what is known as "neutron activation" analysis.

Those tests proved inconclusive, but later tests by chemist Vincent Guinn -- a renowned specialist in neutron activation -- on the bullet lead pointed directly at Oswald. Guinn said the fragments came from just two bullets -- both of which came from Oswald's Russian-manufactured rifle.

Randich said the Lawrence Livermore tests came to a different result.

"We don't know if there were two bullets," said Randich. "There could have been two bullets, but the lead composition data shows there could be anywhere from one to five bullets."

Copyright 2006 by KTVU.com. The Associated Press contributed to this report.

The gunfire occurred about 2 p.m. in a parking lot, near residence halls on the campus' west side. The Penningtons were pronounced dead at local medical facilities.

"We are stunned to hear about this terrible tragedy," University President David Dunlop said in a statement. "Our thoughts and prayers are with the families of the victims."

University spokeswoman Valerie Owens described the campus as quieter than usual this weekend because many students have left for the Labor Day holiday. About one quarter of Shepherd's 4,000 students live in campus residence halls and apartments.

University counselors have been talking to students all afternoon and a formal counseling session on campus Saturday evening. Owens had no information on whether any students or faculty witnessed the shootings.

Shepherdstown is about 80 miles northwest of Washington, D.C., in eastern West Virginia.