The civil suit alleges that Yusuf Abdi Ali, 63 -- a former commander in the Somali National Army who later moved to Alexandria, Virginia -- tortured a Somali national in 1987.
The man bringing the suit claims that, at Ali’s direction, he was beaten, kicked, stripped naked and shot because Ali believed he was a supporter of an opposition group that had recently stolen a water tanker. Ali himself repeatedly shot the man and left him for dead, the suit claims, asking his guards to dispose of the body.
Officials with Master Security, a contractor that provides security guards to the Metropolitan Washington Airports Authority (MWAA), told ABC News they were not aware of the pending civil litigation against their employee until Tuesday, but have now placed Ali on paid administrative leave while they investigate.
The civil suit was first reported by CNN.
According to the Fallston Group, an executive advisory firm hired by Master Security, Ali had worked with the security company "for a couple of years," and had gone through a battery of background checks.
All Master Security employees are subject to "the full, federally mandated vetting process in order to be approved for an airport badge," MWAA said, noting the vetting includes a criminal history record check by the FBI and a security assessment by the Transportation Security Administration. Master Security employees working at Dulles must also be licensed by the Commonwealth of Virginia.
"We have verified that all of these processes were followed and approved in this instance," MWAA said in a statement.
A judge has yet to rule on the case as the courts try to determine whether the U.S. legal system has jurisdiction over the lawsuit, according to the Center for Justice and Accountability. The circuit court dismissed the lawsuit's war crimes claim on the basis that it lacked jurisdiction, it allowed claims of torture and attempted murder to go forward. The case is now awaiting a review by the Supreme Court.
After the alleged war crimes, Ali moved to Canada, but was deported two years later, the suit claims. He then moved to the U.S., where deportation proceedings were begun. He voluntarily left America shortly thereafter in 1994, and returned two years later, according to the suit.
Ali initially came to the attention of investigators and attorneys within the former Immigration and Naturalization Service -- the predecessor agency of the U.S. Immigration and Customs Enforcement -- in the 1990s based upon allegations that he had been involved in human rights violations, according to Gillian Christensen, the deputy press secretary for Department of Homeland Security, which oversees TSA.
"With respect to the individual’s employment at Dulles International Airport, TSA conducted standard security vetting procedures, which are focused on potential threats to national security. TSA provided the full results of its security screening to the Airport Authority who is ultimately responsible for issuing a badge for security contract work. Based on the results of the security screening, he did not meet the criteria for denial of his application," Christensen said.
DHS declined to comment further, citing pending litigation and investigations.
Ali's attorney, Joseph Drennan, denied all allegations and told ABC News that his client, who is still a citizen of Somalia, returned to the U.S. legally.
The conduct that is alleged in this case precedes the passage of U.S. laws regarding extraterritorial war crimes including genocide, torture, child soldiers, according to an FBI spokesman.
The FBI is not involved in an investigation of Ali.
Virginia Commonwealth's Department of Criminal Justice Service was not immediately available for comment.
ABC News' Geneva Sands and Casey Decker contributed to this report.