The latest story involves a high-level staffer in the department of health care finance. The Washington City Paper reports the department's chief of staff, Talib Karim, has had past legal troubles.
It's the same agency where former mayor candidate Sulaimon Brown was hired -- only to be fired last week as questions about his possible criminal past were raised.
Gray has also come under fire for the hiring of children of close advisors, a story first reported on WAMU.
Gray says all of his cabinet picks and department heads were thoroughly vetted. But the same process wasn't used for the lower-level appointments.
"Well, you know, it's easy to be a Monday-morning quarterback and say these are things we should've done," Gray says. "At the end of the day, I'll take responsibility for that. I'm the mayor and the buck stops with me."
Gray says police will review all 270 or so political appointments in his administration.