James Charles Kopp

From CNN Justice Correspondent Pierre Thomas

WASHINGTON (CNN) -- Hair discovered near the scene where a sniper fired the shot that killed Dr. Barnett Slepian is nearly identical to hair thought to belong to James Kopp, the material witness who is being sought in the murder, CNN has learned.

DNA tests conducted on the hair by the FBI strongly suggest it could belong to Kopp, an anti-abortion protester who disappeared after the October 23 shooting in Buffalo, New York.

But sources caution the hair evidence alone is not strong enough to elevate Kopp's status to suspect. And they said even though the hair from the scene was compared to hair taken from a New Jersey residence where Kopp is thought to have lived, they can't be certain about any analysis until Kopp has been located.

"The status of Kopp remains the same," said Buffalo-based FBI spokesman Paul Moskell. "He is still a material witness."

Dr. Barnett Slepian

Moskell said the lethal bullet recovered from Slepian's kitchen, along with bullets from Canada, where three other abortion providers were targeted by snipers in recent years, are at the FBI lab for testing and comparison.

Meanwhile, the FBI continues to search for Kopp. Early in the investigation there was some evidence he might have headed to Mexico, including information a friend may have driven him there. Recently, while in Mexico, FBI Director Louis Freeh asked officials to be on the lookout for Kopp. But sources said the FBI also has been asking Canadian authorities to check out tips that he might be in Canada.

"We have no idea where he is," said one senior official.