Debra Tice is the mother of Austin Tice, an American journalist held captive in Syria. (Jahi Chikwendiu/The Washington Post)

There are many important and scary details that Debra Tice does not know about her son Austin. She has no idea exactly where he is, or who his captors have been since he vanished while reporting in Syria more than four years ago.

But of this, she is certain: Austin Tice is alive, apparently in decent health, and he is being held against his will somewhere in Syria.

“I’m trying to reach whoever is holding him and compel them to realize, it’s time to release him and let him come home,” Tice said Tuesday in an interview in Washington, where she is set to attend the unveiling Wednesday of a banner in her son’s honor at the Newseum.

The banner displays a photo of a smiling Austin Tice, his sunglasses pushed up jauntily on top of his head, and the succinct description of his situation: “Held captive for being a journalist since August 2012.”

It is to remain on the Newseum’s facade until he is returned safely to his family in Houston. Unless he is released before Inauguration Day, the new president will go directly past the banner on the way to and from the Capitol.

Austin Tice, who has contributed to The Washington Post, is one of at least 430 journalists and citizen journalists being held around the world, according to Reporters Without Borders. (Family photo)

“We’re very conscious of our place on Pennsylvania Avenue,” Newseum President Jeffrey Herbst said. “Our role is to bring his cause to the public. I think we’re fulfilling our mission, making sure people know that someone who wanted to inform the world of what’s happening in Syria is still missing.”

According to Reporters Without Borders, at least 430 journalists and citizen journalists are being detained around the world, either by governments or as hostages. Tice is the only American reporter among them.

A handful of countries account for many of the imprisoned reporters on the list. Turkey alone is responsible for jailing at least 130 reporters since a crackdown on the media in the wake of a failed coup in July. The other countries high on the list are China, Iran, Egypt, Vietnam and Syria.

Tice, a former Marine who is now 35, was a freelance reporter whose stories from Syria appeared in The Washington Post, McClatchy and other news outlets. His family has never received any ransom demands. The only time his captors have reached out to prove they had him was six weeks after he disappeared, when they posted a brief YouTube video showing him being led blindfolded up a rocky hillside surrounded by gunmen. He was reciting a Koranic verse in Arabic when he interjected in English, “Oh, Jesus. Oh, Jesus.”

Early in his captivity, there were reports that he had been taken by the Syrian regime. State Department officials have also said that they believe he is in the custody of the government. But lately they have had nothing new to report, and the Syrian government has denied holding Tice or knowing where he is.

Debra Tice said she cannot reveal all that she has learned about her son’s situation without endangering him, but said she believes that he is not being held by antigovernment rebels or Islamic State militants. That leaves the government, or forces loyal to it.

She admits to being frustrated that her son’s plight has not received more attention from the American public, and she said she hopes the Newseum banner changes that.

“In France, when someone is missing, the family expects to hear from the president immediately, and a banner is put up,” she said. “I’ve wondered, where are the banners for Austin?”

She said the Obama administration has been helpful and collaborative since adopting a new hostage policy in 2015 and naming a special hostage envoy. Debra and Marc Tice met with President Obama in July, and he assured the parents that he is committed to their son’s safe return. She holds out hope that it will happen before Obama leaves office in January.

“Austin’s captors have to reach out and let us know what they expect,” she said. “They need to be aware, this is an opportunity. It could be quite a long period of time before they are able to approach a new administration.”

One thing that the past four years have taught her, she said, is that many Americans are apathetic to the danger journalists sometimes face.

“I consider the banner at the Newseum to be a call to Americans to protect and respect journalists,” she said. “Austin’s captivity and the lack of passion about getting him home represents a complacency about journalists. Where do we hear the relentless voice calling for the release of this journalist? Where do we see the counter on TV that’s a piece of our daily bread? This journalist has spent 1,451 days in captivity. It’s appalling.”