Federal officials say they withheld publicizing charges against the accused man until they were certain that he acted alone.

Investigators learned that his flight was set for Dec. 4 from RDU with a return flight to the Triangle on Dec. 18. An FBI special agent noted that White likely purchased a round-trip ticket to avoid arousing suspicion, a common practice among Islamic extremists.

A Durham man was charged by federal authorities with supporting ISIS and later attempting to join the group, according to court documents that were unsealed on Tuesday.

The U.S. Attorney’s Office and the FBI said 29-year-old Alexander White tried to make financial transactions in support of ISIS camps. Investigators said they found out about White from an overseas source who saw him posting online under the name “Sulaiman Al-Amriki,