PHOENIX – A team of federal investigators swept into Phoenix last month amid allegations of a disturbing cover-up at the veterans hospital.

Their goal: to unravel the truth behind a secret waiting list supposedly maintained to hide lengthy delays for sick veterans, making it appear as if they were seeing doctors sooner when some may have waited months and died in the meantime.

The claims, which so far have not been proved, have thrown the U.S. Department of Veterans Affairs into turmoil. Politicians have called for resignations, congressional inquiries are underway, and VA Secretary Eric Shinseki is appearing before a Senate committee in Washington this week.

And it’s only the beginning. Shinseki has ordered an audit of every VA facility nationwide and similar claims of waiting-list manipulations have cropped up in other states. As the election-year talk surrounding the debate rages, here is a look at some key facts about the issue:

HOW DID THE ALLEGATIONS COME TO LIGHT?

A former clinic director for the VA in Phoenix started sending letters to the VA Office of Inspector General in December, complaining about systematic problems with delays in care.

“The time is now. The place is Phoenix, Arizona where a message needs to be sent loud and clear to VA administrators and bureaucrats alike that the murder of our veterans for cash bonuses and career advancement will no longer be tolerated,” wrote Dr. Samuel Foote, who retired after spending nearly 25 years with the VA.

Foote later took his claims to the media, then to Republican Rep. Jeff Miller, chairman of the House Veterans’ Affairs Committee, who announced the allegations at an April hearing.

Foote says up to 40 veterans may have died while awaiting treatment at the Phoenix hospital and that staff, at the instruction of administrators, kept a secret list of patients waiting for appointments to hide delays in care. He believes administrators kept the off-the-books list to impress their bosses and get bonuses.

“If you died on that list, they could just cross your name off and there was no trace that you’d ever been to the Phoenix VA,” Foote told The Associated Press. “As if you never existed. You’re just gone.”

Since Foote’s revelations, two more former Phoenix VA employees have made the same claims.

But some question their motives. One employee, who first raised the concerns publicly a few weeks ago, was fired last year and has a pending wrongful termination lawsuit against the hospital. Before he retired, Foote was reprimanded repeatedly for taking off nearly every Friday, according to internal emails he provided the AP.

He said the reprimands were unfair and that he was overworked and had every right to take the days off. Managers said it looked bad for a clinic director to work just four days a week.

WHAT IS THE VA’S RESPONSE?

Phoenix administrators vehemently deny the allegations. The VA announced recently it found no evidence to substantiate the claims after an internal probe.

The Phoenix hospital’s director, Sharon Helman, scoffed at the notion that she would direct staff to create a secret list and watch patients die in order to pad her pockets.

“To think that any of us would do anything like that to harm any veteran for any financial reasons is very, very disturbing,” Helman told the AP hours before placed on leave while the Inspector General’s Office investigates. She has been provided with police protection after receiving numerous death threats.

Last year, Helman was awarded a $9,345 bonus in addition to her $169,000 annual salary.

Helman and hospital Chief of Staff Dr. Darren Deering, who remains in his job, said Foote and others have not provided names of any of the 40 patients or any documentation of a secret list. Foote, who would not provide that information to AP, said he obtained it through other employees at the VA. He won’t say who.

Helman and Deering also speculated that if up to 40 patients did indeed die while awaiting doctor’s appointments, some may have died from car accidents or heart attacks or other ailments unrelated to their care at the Phoenix VA facilities.

THE FAMILIES

Grieving family members of dead veterans have joined politicians from both parties in protests over VA care. Several of them shared the stage with Sen. John McCain last week at a town hall meeting.

Many are appalled to think that their loved one might have been on a secret list while waiting to see a doctor.

Sally Barnes-Breen said her 71-year-old father-in-law, a Navy veteran, died while awaiting an appointment at the Phoenix VA. Thomas Francis Breen had bladder cancer and died Nov. 30.

Barnes-Breen said she took him into the Phoenix hospital with blood in his urine in September. He was examined, she said, and sent home, told they would get a call for an appointment to see a primary care physician within a week.

But the days came and went and the phone never rang. She said she followed up repeatedly, but no one responded.

“They left him to die,” Barnes-Breen said during a recent interview while cradling a wooden box containing her father-in-law’s ashes.

In early December, a few weeks after Breen died, Barnes-Breen said she finally got a call from the hospital with an available appointment.

“I said, ‘Well, you’re a little too late,”’ she said.

VA administrators in Phoenix declined to discuss Breen’s case, citing privacy laws.

WHAT IS THE OVERALL STATE OF THE VA?

The VA operates the largest integrated health care system in the country, with more than 300,000 fulltime employees and nearly 9 million veterans enrolled for care.

The Phoenix claims are the latest to come to light as VA hospitals and clinics around the country struggle to handle the enormous volume. VA facilities in South Carolina, Florida, Pennsylvania, Georgia and Washington state have been linked to delays in patient care or poor oversight. An internal probe of a Colorado clinic found that staff had been instructed to falsify records to cover up delayed care at a Fort Collins facility.

The VA has acknowledged that 23 patients have died because of problems related to care since 1999, according to an ongoing nationwide internal VA review, which showed that delays often occur when a doctor refers a patient to another physician, such as a specialist. During the same time period of the deaths, more than 250 million of these consults were requested.

The White House said the VA has made tremendous progress in reducing case backlogs, but that they need to be completely eliminated. President Barack Obama has said he remains confident in Shinseki’s leadership.