The family of Julian Assange spoke out about his detention at Belmarsh, a high-security prison in the UK over the publication of classified materials and a new documentary about his case. They stressed that his prosecution could affect press freedom.

The Australian citizen faces a sentence of up to 175 years in an American maximum security prison for facing several charges, including alleged espionage. 

The WikiLeaks founder is accused of publishing classified information detaining crimes committed by the US government in the Guantánamo Bay detention camp, as well as in Iraq and Afghanistan. The information exposes the CIA for engaging in torture and rendition. 

Read more: Julian Assange files appeal against US extradition

The detainee's father and brother, John and Gabriel Shipton, said he is garnering more support from the international community.  "We have a rising tide worldwide of support," John Shipton said Thursday on "Tucker Carlson Tonight." 

He added that the Australian government is more vocal in advocating for his son's release. "We characterized the previous election of the government in Australia as an Assange government because each of the successful candidates and the independents and the Greens stood on a platform of bringing Assange home to Australia," he said. 

Several news outlets wrote an open letter calling on the US to end its prosecution of Assange citing concerns over press freedom, including The Guardian, The New York Times, Le Monde, and Der Spiegel.

Television Host Tucker Carlson asked Gabriel Shipton who was stopping Assange's release, to which Gabriel responded, "Well, the national security DOJ are the ones who are behind this prosecution of Julian."

"I think if they would relook at this case and realize that they are prosecuting someone for doing what journalists do every day – publish. Or what they should be doing – publishing without fear or favor – then they would realize that this prosecution needs to come to an end and that they should listen to outlets like yours, as well as the New York Times, as well as many other groups, human rights groups, free press groups and First Amendment advocates who are all calling for this prosecution to be dropped because of the threat that it poses to the First Amendment in the USA."

Human rights organization, Amnesty International, strongly condemned Assange's detainment. "Julian Assange’s publication of disclosed documents as part of his work with WikiLeaks should not be punishable as this activity mirrors conduct that investigative journalists undertake regularly in their professional capacity," a press release from the organization read. 

John Shipton wondered why the US government advocates for free speech under the First Amendment but then persecutes someone working as a journalist. 

Read more: Belmarsh Tribunal: Biden 'hypocrite' for extradition of Assange

"Why they want to truncate their own magnificent gift to humankind has got us beat. But we keep on, and we keep on getting more and more support," he told Carlson.