Veterans Affairs Secretary Bob McDonald formally apologized this week for a Legionnaires Disease outbreak at the VA Medical Center in Pittsburgh that claimed six lives in 2011 and 2012.

"On behalf of VA I'm deeply sorry for what happened. I'm sorry to the veterans who were affected and their families, to the families who lost loved ones and to those who lost confidence in the VA health care system," McDonald said on Monday.

The VA chief's remarks followed his speech earlier in the day before the annual convention of the Veterans of Foreign Wars in Pittsburgh.

President Barack Obama, who also spoke to the gathered veterans, called the outbreak a tragedy.

"And whenever there are any missteps, there is no excuse," he said.

In addition to the six veterans who died, another 16 were sickened by the bacteria, which contaminated the hospital's water system.

A 2013 investigation into how the outbreak was handled by the VA found no evidence of obstruction or false statements by VA officials or employees and no one was charged. But in November 2014, after VA took another look at the events, it fired the hospital's director, Terry Gerigk Wolf for "conduct unbecoming a senior executive."

The 2014 review followed McDonald's appointment as VA secretary and Wolf was the fourth senior executive servicer office pushed out under a law Congress passed specifically to give him greater authority to terminate high-ranking employees.

But then and now Congress has been dissatisfied with how many McDonald has fired.

Of the four executives, only two were fired and two others were allowed to retire. His claim to Congress that some 1,300 VA employees have been fired since he took over has been greeted with skepticism by the House Veterans Affairs Committee, which is pressing McDonald to find out how many of the ex-workers were still in the probation stage of their employment.

McDonald has argued that the new law does not eliminate due process for any employee and that VA is aggressively pursuing those it believes are poor performers or engaged in improper or unlawful activities.

He also suggested that the VA's intention to hold people accountable already has had an impact out in the field, saying "the fact that 91 percent of our medical facilities have new directors and new leadership teams is evidence of that."

Further evidence, he said, is that VA has more than 100 people under investigation for manipulating wait times and data, with one VA supervisor in Georgia charged this week with 50 counts of falsifying medical records.

"These investigations take time, and because they take time it happens over time," he told Military.com on Tuesday.

The investigations have to be handled in a deliberate way, he said, in order to make sure the evidence is there and that a case can be made.

"It doesn't do me any good to do a press conference and say we're doing something, and then it doesn't stick," he said. "Or, if they're able to get off on appeal it will come back to us."

In his speech to the VFW Tuesday morning, McDonald criticized lawmakers for barring VA from moving funds around within its budget and cutting the department's proposed 2016 budget.

He said the moves will make the VA a "place where the needs of veterans are second to ideology, to scoring political points, where VA is set up to fail, a place where there are no winners."

-- Bryant Jordan can be reached at bryant.jordan@military.com