Forensic experts said today the final report they expect to deliver Friday may not state with more than 90 percent certainty that the human remains they examined are really those of the Nazi war criminal Josef Mengele.

"We are doing our utmost to deliver the final report before the weekend," said Jose Antonio de Mello, vice director of the Medical Legal Institute, where bones exhumed June 6 are being examined.

The forensic evidence is needed to confirm that Mengele died in Brazil in 1979. Handwriting samples and other evidence have indicated he lived in Sao Paulo.

"In legal medicine, nothing is certain -- but we can speak of great possibilities, of up to 90 percent," said Mello. "I have a conviction, but conviction isn't certainty and I can only say that at the end we'll communicate the degree of certainty we do have."

Mello said the experts, at a meeting of all involved to compare dental and medical evidence, would render conclusions in a final statement, probably Friday.

Dr. Wilmes Teixeira, coordinator of the 17-member team, appealed yesterday for fresh medical data such as X-rays from doctors or dentists who may have treated Mengele during his two decades in South America.

"Without this information we might take another two weeks and still not be absolutely conclusive. We are now working with hypothesis," said Teixeira. He added that new data received from the Simon Wiesenthal Center in Los Angeles did not allow decisive comparison. Four more teeth, uncovered when the grave was reopened during the weekend, could provide an important advance.

Although a margin of doubt still exists because of forensic difficulties and the absence of fingerprints, European specialists involved in the case say they are satisfied with secondary proofs uncovered by Brazilian police of Mengele's presence.