Late in the afternoon of September 25, 2008, the phone rang in Steve Rotella’s 33rd floor office in downtown Seattle.

The wide bay windows, once part of a conference room, commanded a sweeping view of Puget Sound, befitting the president of the nation’s largest savings and loan.

On a credenza behind his desk, one of his computer monitors quietly streamed ticker symbols.

Washington Mutual’s closing price: $1.69, down 25 percent.

For the past few days, a handful of big financial institutions had been poring over WaMu’s books, trying to decide whether to make a bid and rescue it from potential failure.

Suddenly, they had stopped.

Rotella wanted to know why. He had asked WaMu’s head of regulatory relations, John Robinson, to see what he could learn from the bank’s chief regulator, the federal Office of Thrift Supervision.

Now, Robinson was calling back. “Steve, it’s over,” Robinson said, according to people familiar with the call. “They’re coming in to close us this afternoon.”

Shortly after Rotella hung up the phone, government officials strode through the marble lobby of the newly built WaMu Center and ended the 119-year life of a vast financial enterprise once considered among the strongest and most promising in the country.

Within two hours of the call, regulators took control of a company with $307 billion in assets and sold it to rival JPMorgan Chase & Co. for $1.9 billion, a fraction of what the New York powerhouse led by Jamie Dimon had offered just months earlier.

With these swift actions, tens of thousands of shareholders and bondholders lost billions of dollars, and Washington Mutual became known as the largest bank failure in U.S. history — nearly eight times larger than the Federal Deposit Inurance Corp.’s previous record failure, set during the savings and loan crisis of the 1980s.

Yet despite the size and significance of this event, much of what happened to WaMu has never been reported.

“It was dealt with so surgically and so quickly that in comparison to all of the other things going on, I think this one almost became a non-issue,” said Lewis Mandell, a professor of business and finance economics at the University of Washington’s Foster School of Business.

To recreate WaMu’s final days, the Puget Sound Business Journal examined hundreds of pages of documents obtained through the Freedom of Information Act and interviewed dozens of former WaMu executives and employees, as well as government regulators and outside observers. Many sources would only speak on condition of anonymity. These sources, including insiders who lived through WaMu’s downfall, paint a picture of panic, confusion and futility as events spiraled out of control.

These interviews show that WaMu suffered through not one but two bank runs in its final months. The first run was many times larger than the run that felled California lender IndyMac in July 2008, though neither shareholders nor the public knew about it. WaMu survived that run, and the second run was tapering off when regulators moved in and shut the bank, citing the run as the reason.

In addition, WaMu’s top executives, led by CEO Alan Fishman, were trying to sell the bank after federal regulators imposed a deadline, only to discover that they were being undermined by those same regulators, executives say. The government’s plan to seize the bank, if it became known beforehand, would cause potential buyers to immediately cool their heels, because buying after a government takeover would be a lot cheaper than even the desperate private purchase deal that Fishman was seeking.

The takeover of WaMu prevented a potentially catastrophic hit to the deposit insurance fund. In that sense the seizure was a success: Not a dime of the FDIC’s then $45 billion fund went to reimburse WaMu depositors because JPMorgan Chase had taken over.

Yet even a year later, fundamental questions remain unanswered. And in part because regulators have said so little about their actions, there remains a voracious appetite to get to the bottom of why WaMu failed.

A slew of inquiries is under way. The Federal Bureau of Investigation and the U.S. Attorney’s Office in Seattle launched a large-scale investigation last October that is ongoing. The bankrupt holding company was recently given permission to subpoena hundreds of pages of documents from JPMorgan as part of its discovery process. The purpose of that investigation, which could take months, is to shed light on JPMorgan’s actions in the weeks leading up to its purchase of the bank, according to a spokesman for WaMu’s holding company.

Recently, the Inspector General’s office at the U.S. Treasury, the department that houses the Office of Thrift Supervision, launched a “post mortem” investigation jointly with the FDIC’s inspector general, “to see if there was anything that could have been done” to save WaMu, said Rich Delmar, counsel to the Treasury department.

“The IG offices typically don’t investigate cases where there was no cost to the insurance fund,” Delmar added. “But because this was so damn big, we’re doing it anyway.” The results are expected as early as next month.