ABC news has confirmed internal emails, in which a CDC employee wrote that doors were left unlocked to areas where scientists test potential biological weapons.
The Atlanta lab holds deadly germs like anthrax, monkey pox, virulent flu strains and SARS. The security lapses happened multiple times in 2009 and 2010.
"You don't want things getting out of the laboratory, there is people in the halls, people outside the lab that aren't wearing any of the protective equipment," said Dr. Richard Besser, ABC News' Chief Health and Medical Editor and Former Acting Director of the CDC.
The CDC tells ABC News it has addressed the incidents at the lab and that the public was never at risk. But critics are calling for an outside agency to step in and ensure the top secret labs are safe.