UPDATE 1-US Air Force arms buyer's autopsy could take weeks

(Adds Boeing comment, paragraphs 8-9)

By Jim Wolf

WASHINGTON, Oct 16 (Reuters) - Determining the cause of death of the U.S. Air Force's second-highest-ranking weapons buyer may take several weeks, the medical examiner's office said on Tuesday.

Charles Riechers, 47, was found dead at his Chantilly, Virginia, home on Sunday in an apparent suicide, an internal Air Force memorandum said.

Nancy Bull, district administrator for the northern regional office of Virginia's chief medical examiner, said it could be weeks before a ruling was made on the cause and manner of death.

"Sometime the tests do take that long," she said. "We're waiting for results of an investigation that's ongoing."

Riechers had been facing scrutiny after The Washington Post reported the Air Force arranged to have him paid about $13,400 a month by a contractor, Commonwealth Research Institute, while he awaited final clearance as the principal deputy assistant secretary for acquisition.

Riechers' ties to Commonwealth Research, registered as a nonprofit in Johnstown, Pennsylvania, sparked new questions last week about a disputed $1.2 billion contract awarded to Boeing Co (BA.N) for depot maintenance of the KC-135 refueling tanker fleet.

Pemco Aviation Group PAGI.O on Friday amended its protest to the Government Accountability Office over the contract, which fell under Riechers' purview. It raised questions about a possible conflict of interest because of purported ties among Commonwealth, its corporate parent, Concurrent Technologies Corp., and Boeing.

A Boeing spokesman in St. Louis, Forrest Gossett, said a company called Concurrent Technologies Corp "has done work with Boeing in the past."

"We're trying to determine the exact nature of the work," he said, adding Boeing had thousands of suppliers.

The Air Force had no immediate comment on any conflict-of-interest reviews it might have launched in the matter. A Pemco spokeswoman, Doris Sewell, declined to comment.

A Concurrent Technologies spokeswoman did not immediately respond to an inquiry about any work with Boeing, the Pentagon's second-largest contractor after Lockheed Martin Corp (LMT.N).

Riechers had been involved with top acquisition programs, including a $40 billion competition between Boeing, on the one hand, and a Northrop Grumman Corp (NOC.N)-EADS (EAD.PA) team on the other, for an aerial refueling tanker fleet. That contract is due to be awarded late this year or early in 2008. (Reporting by Jim Wolf)