In June, federal officials launched an investigation into who ordered a delay in the closing of Silverado Banking, Savings and Loan, the failed Denver thrift where President Bush's son Neil was a director. They wanted to know why the government waited until after the 1988 presidential election to shut it down.

Three months later, key individuals involved in the decision to delay the closing say they have not yet been contacted by federal officials conducting the inquiry.

The investigation by the Treasury Department began June 29, two weeks after a former thrift field supervisor testified under oath that officials in Washington ordered him to wait two months -- until after the November election -- before shutting down Silverado. So far, the former supervisor said yesterday, except for reporters, no one has asked him a question about his testimony.

"I haven't been contacted," said Kermit Mowbray, former president of the Federal Home Loan Bank of Topeka, Kan., and the government's chief regional thrift supervisor for a four-state region that included Colorado.

Other key officials in the Topeka office also have not been questioned, according to government sources familiar with the investigation. As far as the Topeka office is concerned, the investigation "has gotten off to a slow start," said one person familiar with the inquiry.

A spokesman for the Treasury, which last year took over responsibility for supervising thrifts, would not comment yesterday on why Mowbray or others have not been contacted or questioned by the agency. She would only say the investigation is continuing.

In the meantime, officials involved in the decision who are still in the government have been ordered not to discuss the case publicly as long as the government considers the investigation to be alive.

Key people who in 1988 were in the Washington headquarters of the Office of Thrift Supervision, then called the Federal Home Loan Bank Board, have already said they don't recall how the decision was made to delay the closing of Silverado, whose failure is expected to cost taxpayers more than $1 billion. Among those who have said publicly that they don't recall are M. Danny Wall, the nation's chief regulator from mid-1987 until December 1989; Stuart Root, chief of the thrift deposit insurance fund under Wall; and Karl Hoyle and Mary Creedon, top officials at the agency at the time.

Mowbray said that in July 1988 he informally told Washington officials that Silverado's health had deteriorated to the point where the government soon would have to take it over.

In September, his office formally requested that the thrift be seized by the federal government. Officials in Washington didn't respond to the request until mid-October, when they accepted the recommendation but asked the Topeka office to delay the closing for two months.

According to government sources, a government memorandum and publicly available information, former government thrift official Jay Earle made the telephone call requesting the delay because the government did not have the manpower to act earlier. The call followed up on an Oct. 20, 1988, memo he had written to formally notify the Topeka regulators that Washington intended to close Silverado.

Earle could not be reached for comment.

Earle made the call to Topeka regulator Lou Roy, who then passed the information along to other Topeka officials, who then passed it along to Mowbray. Treasury officials have refused to allow Roy to discuss the matter.

Mowbray said that there is no significance to the fact that it took until Nov. 9 -- 20 days after Earle's memo was faxed to the Topeka bank and one day after the election -- before he signed the letter that set in motion the plans needed for the government physically to walk through Silverado's doors and take control.

"As far as I am concerned, it was happenstance," Mowbray said.

Still unanswered, however, is how officials in Washington made the decision to delay the closing. Mowbray and others insist that no political pressure was ever put on them from Washington or anywhere else to delay the closing.

The thrift regulatory system, in general, tolerated political activities that would not be allowed elsewhere.

For example, Mowbray once solicited campaign contributions from his 11 other regional thrift regulators around the country for former senator David Karnes, a Republican from Nebraska. Mowbray defends the action as appropriate. Regulators of commercial banks would be reprimanded for such an action, according to government spokesmen.