Austin Tice disappeared in Syria on Aug. 13, 2012, and 911 days later, the freelance journalist is still missing. Now his parents have launched a new campaign to bring their son home.

On Tuesday, the White House confirmed that there is at least one American still being held in the Middle East, and though Press Secretary Josh Earnest did not elaborate on who that person is, all signs point to Tice.

The confirmations came the same day that the family of another American, 26-year-old aid worker Kayla Mueller, confirmed her death. Mueller had been held by Islamic State (ISIS) militants in Syria since August 2013, though her official cause of death has not yet been determined. As news of Kayla Mueller's death broke on Tuesday, Tice's mother tweeted her condolences to the family.

May Kayla rest in peace. Our hearts are breaking for the Mueller family. — Debra Tice (@DebraTice) February 10, 2015

Who is Austin Tice?

Tice, of Houston, Texas, disappeared in August 2012 while covering Syria's civil war. It's not clear what group is holding him, but it is not believed to be the Islamic State group or the Syrian government, his family has said.

Before becoming a journalist, Tice was a Marine from 2005 to 2011. He served in Afghanistan in 2011, tweeting photos of his time in service.

7 months ago we flew east to Afghanistan. Yesterday we flew east to get home. 7 months that changed my life forever. pic.twitter.com/wl7ffUHq — Austin Tice (@Austin_Tice) December 11, 2011

Prior to his disappearance he was working as a freelance journalist, and his work was published by the McClatchy Newspapers, the Washington Post, Associated Press, and AFP. Tice received the 2012 George Polk Award for War Reporting and the 2012 McClatchy Newspapers President’s Award for his coverage of the Syrian conflict.

Many details around his disappearance still remain murky. On Aug. 13, 2012, two days after his 31st birthday, Austin disappeared. Tice was preparing to travel from the city of Daraya, just south of Damascus, to Beirut, Lebanon, at the time that he went missing. Up until that point, Tice had been active on social media, regularly posting about his experiences in Syria. His final tweet on Aug. 11 recounted how he had spent his birthday at a party with Free Syrian Army fighters that day.

Spent the day at an FSA pool party with music by @taylorswift13. They even brought me whiskey. Hands down, best birthday ever. — Austin Tice (@Austin_Tice) August 11, 2012

In 2012, a video circulated showing Tice being held by armed men. The video immediately triggered questions from specialists on the region, who initially said the Syrian regime of Bashar al-Assad was behind the abduction. In the footage, Tice can be heard reciting a prayer in Arabic before saying, "Oh Jesus, oh Jesus" in English.

Two years to the date of his disappearance, Tice's parents published a letter to their son, saying they have had no contact from him or his captors since the time of his disappearancer, and they did not know where he was or who was holding him.

His parents said they had been told by "credible sources" that Austin Tice is alive, reasonably well treated and that they need to be patient.

"There's a general confidence that he will come home safely," Marc Tice said. "That's about as much detail as we have."

Next week, the family plans to launch the Free Austin Tice campaign in conjunction with Reporters Without Borders to raise awareness for Tice and to urge the U.S. government to take action on his behalf.

The online campaign is supported by USA Today, McClatchy Newspapers and other media outlets. It will feature a series of ads with the message "Free Austin Tice." His parents are also encouraging supporters to sign a petition to President Barack Obama to work on bringing Tice safely home.

As part of the campaign, the family is asking supporters to don a black blindfold and share their image on social media with the hashtag #FreeAustinTice to raise awareness.

"I hope it will contribute to bringing him back home, and I think [it] is a very important moment because he is the only American journalist still missing in Syria and we can bring him back home," said Delphine Halgand, the U.S. director for Reporters Without Borders.

During a briefing last week, Tice's parents said they are taking part in meetings for a White House policy review on how to handle hostage cases.

"After almost two-and-a-half years ... we feel like we need to let everybody know that our son is missing — and will you please help us get him home?" Debra Tice pleaded during a news conference at the National Press Club.

Additional reporting provided by the Associated Press.