Under the guidance, people who are exposed to someone infected are allowed back on the job if they are asymptomatic.
The senators want a written explanation for the removal of the intelligence community inspector general who flagged the Ukraine complaint.
Federal prosecutors say Peter Lucas, 35, stole at least four boxes each containing 50 surgical masks from the facility in March.
He resigned shortly after taking the 35-hour trip aboard a Gulfstream 550.
The bodies of a university doctor and her husband were found in a ditch last week. They had been shot in the head.