Call it the case of the missing marching order.

M. Danny Wall, the nation's chief thrift regulator from mid-1987 until December 1989, doesn't remember it.

Karl Hoyle, a top aide to Wall, doesn't remember it.

Mary Creedon, also a top official under Wall, doesn't remember it.

After two days of searching, neither former nor present federal regulators were able to come up with the name yesterday of the person who placed a telephone call in October 1988 ordering a field regulator in Colorado to wait two months -- until after Election Day -- to close a failing Denver thrift where President Bush's son Neil had been a director.

Bill Fulwider, a spokesman for the Office of Thrift Supervision, the division of the Treasury that regulates the savings and loan industry, said he did not know the answer, was still checking and was not sure how long it would take to get it.

Fulwider said that several people who might have been expected to know the answer either did not or could not be reached yesterday.

Kermit Mowbray, the former top regional regulator for thrifts in a four-state region that includes Colorado, raised the issue Tuesday when he testified under oath before the House Banking Committee. Mowbray said that officials in Washington ordered him to wait to close Silverado Banking, Savings and Loan Association, where Neil Bush had been a director from mid-1985 until mid-1988. Mowbray complied with the order, waiting until the day after George Bush was elected president to issue the takeover order. Regulators didn't actually seize Silverado, which is expected to cost taxpayers $1 billion, until Dec. 9.

The delay was ordered despite a request by field supervisors that action should be taken right away, Mowbray testified. Mowbray said he could not remember who placed the call, or who on his staff received it. The members of the staff of House Banking Committee Chairman Henry B. Gonzalez (D-Tex.), who held Silverado hearings, also have been unable to come up with the name of the person who made the call.

No former or current government officials contacted yesterday could recall who made the call.

Wall said he has "no recollection" concerning the delay and that he doesn't even know if its true that a delay was requested.

Wall's aide, Hoyle said, "My only recollection was that lots of deals were being done in 1988. There was an incredible amount of work and a limited number of people."

Hoyle said he is aware that many people in Congress believed that he and Wall, for years the top banking aide to Sen. Jake Garn (R-Utah), were very political in their outlook and their actions as thrift regulators. "I can appreciate that," he said. "But the truth is we never did anything political. It happens to be the truth."

As to whether officials in Washington were aware that the president-elect's son had been a director of Silverado, Creedon said, "People were certainly aware of it, but I don't know of any political factors driving the timing of the case."

While she did not know who placed the call, or even if Mowbray's account that a call was made was correct, she said the likely factors driving the timing of actions on failing thrifts were: How much money an institutions was losing; how strong a case regulators could make for seizing an institution; and whether the government fund that insures deposits at thrifts had sufficient cash to undertake such a closure.