Stung by revelations that a mole may have compromised a report issued earlier this year about the FDA’s Office of Criminal Investigation, the US Government Accountability Office is now conducting an internal probe into the leaks, which recently prompted US Senator Chuck Grassley to chastise the agency and demand an investigation.

The move, according to a congressional source familiar with the situation, comes just one week after Terry Vermillion announced he would retire next month as head of the FDA’s OCI (look here). The GAO report (look here) found the FDA’s OCI suffers from lax oversight, despite increased in funding and staffing over the past decade, although several of the complaints were leveled specifically at Vermillion, who is a retired Secret Service agent. We await a response from the GAO and will update you. UPDATE: A GAO spokesman writes us 3 pm ET to say the agency probe is not yet complete.

Grassley, however, recently asked the GAO to learn how a mole was able to purportedly compromise some of the findings. The senator was tipped off by an unnamed whistleblower, who subsequently revealed several allegedly troubling details concerning Vermillion. For instance, Vermillion relocated his domicile to the Hampton, Virginia, area and directed OCI work predominantly over the phone.

He also allegedly used OCI technical support staff and his IT staff to do personal work for him; and he allegedly authorized payment for government contracting training at George Washington University for a fellow OCI employee characterized as his ‘office mistress.’

And according to Grassley, Vermillion also allegedly directed reports prepared by OCI’s Office of Internal Affairs were sanitized of derogatory info about his fellow US Secret Service retirees now working at OCI, and regularly had OCI training session and conferences held in the Dallas, Texas area so that he could visit family - a son and grandchildren, the letter states