Austin Tice's family has not heard from him in more than two weeks.
The freelance journalist traveled to Syria to cover the country's civil war, but his whereabouts have remained unknown since mid-August. Diplomats from the Czech Republic are working on the United States' behalf to locate the 31-year-old McClatchy contributor.
The ambassador to the Czech Republic said that Tice is believed to be alive and is being held near Syria's capital, Damascus. McClatchy's Hannah Allam reported that Tice, who is also a former U.S. Marine, is "likely being held by the Syrian government."
Local family and friends gathered together in Tice's hometown of Houston over the weekend to call for the journalist's release.
Like many journalists covering the violence in Syria, Tice entered the country without a visa. He has contributed reports to the Washington Post and CBS News. According to the Committee to Protect Journalists, Tice has been covering the uprising in Syria since May.
According to his Twitter profile, which the journalist frequently updated, the last message Tice sent was on August 11. "Spent the day at an FSA pool party with music by @taylorswift13. They even brought me whiskey. Hands down, best birthday ever," he wrote.