WASHINGTON -- A senior federal banking regulator has been removed from his job after government investigators concluded that he knowingly permitted IndyMac Bancorp to present a misleading picture of its financial health in a federal filing only months before the California thrift was seized by regulators.

The Office of Thrift Supervision removed Darrel Dochow as director of its western region, where he was responsible for regulating several of the largest banks that failed or were sold in the last year, including Washington Mutual, Countrywide Financial, IndyMac and Downey Savings and Loan.

Mr. Dochow allowed IndyMac to count money it got in May in a report describing its financial condition at the end of March, according to an investigation by the Treasury Department's Inspector General, Eric Thorson, which was described in a letter from Mr. Thorson.

Mr. Thorson wrote that OTS, one of four federal agencies that regulates banks, allowed other companies that it oversees to perform a similar legerdemain, though he did not name those companies.

Mr. Dochow did not immediately respond to requests for comments.

An OTS spokesman did not immediately return a call or an e-mail. In a letter to the Inspector General, the head of OTS, John Reich, described Mr. Dochow's actions as a "relatively small factor in the events leading to the failure of IndyMac." Mr. Reich said he had assigned Mr. Dochow to work on "special projects and administrative issues" while Mr. Thorson completes his investigation.

The findings raise new questions about OTS's regulation of the thrift industry, composed of banks that concentrate on mortgage lending. Last month, The Washington Post reported that close ties between regulators and companies played a role in the collapses of several of the largest thrifts, including IndyMac. Regulators allowed companies wide latitude and failed to insist on changes even when problems became apparent.

"The role of the Office of Thrift Supervision, as the name says, is to supervise these banks, not conspire with them. Capitalization requirements are there for a reason, and the failure of IndyMac cost the federal deposit insurance system $8.9 billion," said Sen. Charles Grassley, R-Iowa, who was briefed on the findings by Mr. Thorson. "It's good the Inspector General has opened a full-blown audit as a result of this case. Everyone ought to be paying very close attention."