Mr. Opfer's office also will look more broadly at Legionnaires impact across the entire VA health system nationwide, Mr. Casey's office said.
"I'm pleased that the VA Inspector General has opened an investigation into the Legionnaires' outbreak at the VA Pittsburgh Health System," Mr. Casey said in a news release. "It's critical that the VA be held accountable and that reforms are instituted so this never happens again in Pittsburgh or any other VA facility."
The Pittsburgh VA reported on Nov. 16 that it had four patients who contracted Legionnaires' disease at its University Drive hospital in Oakland, and all four had recovered. Six days later it said it identified a fifth case. The patient in that case died a day later, on Nov. 23.
In addition, two other Pennsylvania families believe that men in their families died after contracting Legionnaires' at either University Drive or the VA's H.J. Heinz nursing home near Aspinwall. Neither of those two cases has yet been confirmed to have originated at a VA facility.
Cathy Gromek, a spokeswoman for the inspector general's office, said not only did Mr. Casey request an investigation, but also VA Secretary Eric Shinseki made a request last week to the inspector general.
She said Mr. Opfer, whose office is independent of the VA, was not obligated to take up the request but agreed to do so.
Ms. Gromek said the office prefers to refer to actions like this as a "review" rather than an "investigation," as Mr. Casey referred to it. That's because it will be performed by the office of health care inspection, which is staffed by medical professionals, not criminal prosecutors.
Although the inspector general's office formally agreed to the investigation in a letter Friday to Mr. Casey's office, it had already begun doing background work on Monday after getting the request on Dec. 14, Ms. Gromek said.
The inspector general hopes to complete the report by the end of January or early February, she said, with the VA having two to four weeks to respond before the report is made public.