The operations director of the Medical Examiner's office, Ray Blackeney, said the severed leg was found after the last three identified bodies were removed from the building, an operation that was delayed until after the building was demolished because of fears that the structure would collapse.

At the time of the recovery of the three bodies, Mr. Blackeney had dismissed the possibility that a bomber was killed in the blast, saying: "As far as I'm concerned, he's not there. We have found the people where we thought we would find them. We didn't find anybody we didn't think was there."

Because the leg was found after the building was demolished by controlled explosions on May 23, it may be difficult to determine its original location. But because the area above the three bodies was thoroughly searched, and the wreckage sealed off and guarded, it would appear that the leg had been further down in the rubble, near the center of the blast. That location would be consistent with someone in or near the exploding truck. Further, Mr. Blackeney said the leg was the largest identifiable body part, suggesting that the rest of the individual had disintegrated from the force of a nearby explosion.

The "olive drab blousing strap" mentioned in the Medical Examiner's report is a thin elastic band commonly used in the military to "blouse" trousers by tucking the bottoms around the strap and pulling them down over the tops of high combat boots for a neat appearance.

The military personnel -- mostly recruiting officers -- inside the Federal Building were all accounted for. However, a veteran or someone who, like Mr. McVeigh, favored military garb might be likely to use blousing straps.

Asked in a telephone conversation why the Medical Examiner's office had not made the existence of the severed leg public before, Mr. Blackeney replied; "Why should we?"

"I knew about it," he said. "We all knew about it here at the Medical Examiner's."

He said that the Medical Examiner's technicians had been working with the Federal Bureau of Investigation using DNA and other tests on the severed leg and other pieces of tissue in hopes of establishing identifications.

"This has come out a little bit premature," Mr. Blackeney said. "This is the last piece of the puzzle and I hope at some point to offer an explanation."