A former FBI linguist was arrested over the weekend on charges that he lied to investigators by denying that he had contact with a suspect in a terrorism investigation.

Abdirizak Jaji Raghe Wehelie, 66, of Burke, Virginia, was arrested Saturday night when he arrived on a flight at Dulles International Airport outside Washington. He was charged with obstructing an investigation and making false statements to the FBI.

Court documents said that in 2016, Wehelie was translating messages captured by court-ordered surveillance of a suspect's cellphone. One call was a message the suspect left on Wehelie's own voicemail system. But in his notes on the call, the documents said, Wehelie marked the person who called as "UM," meaning unidentified male — failing to note that he, himself, was the recipient of the message.

Investigators said Wehelie was questioned about it, denied having other calls with the suspect, and said he did not know the person well. But investigators said the two were in phone contact with each other as early as 2010, and Wehelie later admitted that he had known the suspect for years.

Law enforcement officials said the FBI was monitoring the calls as part of its investigation of another man, a former Virginia cab driver who left the United States to join the al-Shabab terror group in Somalia. Liban Haji Mohamed was briefly on the FBI's list of most-wanted terrorists. He was reportedly detained in Somalia in 2015 but has never left that country.

Wehelie was due in court in Alexandria, Virginia, on Monday afternoon to formally face the charges.