Orlando nightclub terrorist worked for major DHS contractor that secures “90 percent of U.S. nuclear facilities.”

The Orlando nightclub terrorist who pledged allegiance to ISIS worked almost a decade for a major Department of Homeland Security contractor, raising alarms that ISIS sympathizers and agents have infiltrated the federal agency set up after 9/11 to combat terrorists.

Officials say Omar Mir Seddique Mateen, an Afghan-American who held two firearms licenses and a security officer license, was employed by the security firm G4S Secure Solutions USA Inc. since Sept. 10, 2007. The Jupiter, Fla.-based company merged with the Wackenhut Corp. after 9/11 and assumed federal contracts.

“G4S supports the U.S. Department of Homeland Security, Customs and Border Protection (CPB), with its operations at the U.S. ­ Mexico border and with U.S. Immigration and Customs Enforcement (ICE) to transport illegal immigrants in selected urban areas,” the company says in a brochure, titled “Providing Manpower Solutions for Government Services.”

The DHS contract with G4S is worth more than $234 million. The contract states that one of the “performance requirements” is helping identify “suspected terrorists” trying to enter the U.S.

The security contractor also provides security guards and other security services for “90 percent of U.S. nuclear facilities.”

G4S uses fortified buses to transport “hundreds of thousands of illegal immigrants” from city to city and from cities to the U.S.-Mexican border. But earlier this month, Judicial Watch revealed G4S has been quietly moving and releasing van loads of illegal aliens away from the border to interior American cities.

The immigrants were classified as OTMs — Other Than Mexican — and included mostly Central American illegals but possibly also foreign border-crossers from the Middle East and Pakistan.

“A security company contracted by the U.S. government is driving the OTMs from the Border Patrol’s Tucson sector, where they were in custody, to Phoenix,” the Washington-based government watchdog group said. “The firm is called G4S and claims to be the world’s leading security solutions group with operations in more than 100 countries and 610,000 employees.”

It’s not clear if the 29-year-old Mateen worked on any federal contracts or dealt with federal inmates. One of his jobs was to help transport and guard state and local prisoner youths in Florida. The subsidiary he worked for — G4S Secure Solutions USA Inc. — is based in Jupiter, Fla., which is located just south of Mateen’s home in Fort Pierce, Fla.

It’s also not immediately known if he had federal security clearances, or what kind of security background check G4S administered before hiring Mateen.

But he continued to guard prisoners despite reports he openly praised ISIS in conversations with co-workers, and even though he had been under federal investigation for terrorism ties since at least 2013.

In a 2012 company newsletter, G4S congratulated Mateen for five years of service.

Attempts to reach G4S representatives Sunday were unsuccessful. But the same company brochure says security officers “are subjected to a stringent background investigation” that includes psychological, background and criminal screening.” Testing for jihadist sympathies is not listed.

“From our superior recruiting, training and education to our background checks and screening, our manned security will exceed your expectations,” the contractor assures federal clients.

G4S, which was the first contract security company to received designation and certification by DHS, also helps the federal government with emergency security responses to “terror threats.”

Employing more than 50,000 Americans, G4S provides security support for several other federal agencies, as well, including the departments of State, Interior, Labor, Justice and Energy, and the IRS and Drug Enforcement Administration. The security firm also partners with the U.S. Army, U.S. Air Force and NASA.

Through the U.S. General Services Administration, the company supplies guards, detention officers, court security officers, baggage handlers, security clerks, and prisoner bus and van drivers in contracts worth hundreds of millions of dollars.

It’s not the first time a federal contractor has employed a major Islamic terrorist.

In 2008, Charlotte, N.C.-based Convergys Corp. came under fire for employing a Muslim computer operator who openly maintained a jihadist website featuring grisly images of American soldiers blown up by al-Qaida terrorists overseas which he said “bring great happiness to me.” Convergys at the time had landed a $2.5 billion federal contract to set up emergency communications centers in the event of terrorist attacks and other disasters.

The employee, 22-year-old Sami Khan, turned out to be an al-Qaida operative. He was killed in 2011 in a U.S. drone strike in Yemen.

Paul Sperry is a Hoover Institution media fellow and author of INFILTRATION: How Muslim Spies and Subversives Have Penetrated Washington. Contact him at [email protected].