The family of missing U.S. journalist James Foley released a statement Friday claiming “with a very high degree of confidence” that he was being held in a Syrian prison.

Foley, 39, was last seen late November in northwest Syria, where he was contributing videos to Agence France-Presse for the media company GlobalPost.

GlobalPost CEO Philip Balboni confirmed that both the company and the family have been in touch with the U.S. State Department, nearby foreign governments and private investigators to acquire more information concerning Foley’s alleged imprisonment. Thus far, they believe Foley was kidnapped by a masked gunman, most likely affiliated with a pro-Syrian government military group. Investigators believe he is being held with other Western journalists in a detention facility near the Syrian capital of Damascus.

Foley’s New Hampshire-based family made this statement at a Boston event celebrating “World Press Freedom Day,” which aims to raise awareness of the difficulties and dangers journalists face worldwide.