Story highlights Yusuf Abdi Ali has been living outside Washington, D.C., for about 20 years

Ali is being sued in civil court for torture; there is no criminal court that has the jurisdiction to try him

(CNN) The local and federal agencies handling American airports could not explain Thursday why an accused war criminal was hired as a security guard at Dulles International Airport despite the fact that authorities knew about the serious allegations against him.

As CNN exclusively first reported on Wednesday, Yusuf Abdi Ali, who is accused of committing atrocities while he was a military commander during Somalia's brutal civil war, has been living outside Washington, D.C., for about 20 years. A CNN camera captured him guarding a security exit where ticketed passengers leave the airport.

Ali and his lawyer have denied all the allegations against him. When CNN approached Ali outside his apartment in Alexandria, Virginia, he declined an interview, saying, "To tell you the truth, all is false. Baseless."

When CNN asked how he was hired, each one of several federal agencies confirmed it knew about Ali's past but refused to give a reason why his background didn't raise red flags.

Photos: Mass grave reveals Somalia's bloody past Photos: Mass grave reveals Somalia's bloody past Hide Caption 1 of 10 Photos: Mass grave reveals Somalia's bloody past Hide Caption 2 of 10 Photos: Mass grave reveals Somalia's bloody past Hide Caption 3 of 10 Photos: Mass grave reveals Somalia's bloody past Hide Caption 4 of 10 Photos: Mass grave reveals Somalia's bloody past Hide Caption 5 of 10 Photos: Mass grave reveals Somalia's bloody past Hide Caption 6 of 10 Photos: Mass grave reveals Somalia's bloody past Hide Caption 7 of 10 Photos: Mass grave reveals Somalia's bloody past Hide Caption 8 of 10 Photos: Mass grave reveals Somalia's bloody past Hide Caption 9 of 10 Photos: Mass grave reveals Somalia's bloody past Hide Caption 10 of 10

Ali works for a contractor, Master Security, hired by the Metropolitan Washington Airports Authority, or MWAA. When CNN initially asked Master Security about Ali, the company said it was "unaware of the pending litigation." In light of the "very serious nature of the allegations," Ali is on administrative leave, and the company is reviewing the case, according to Chief Executive Rick Cucina. Ali's airport access has also been withdrawn.

Read More