The brother of Sean Hoare - the News of the World whisteblower who died in July - insisted today that "everything Sean said was the whole truth".
And he said that his brother believed phone-hacking was daily routine at The Sun, as well as the News of the World.
Hoare, who left the News of the World in 2005, told the New York Times in 2010 about the widespread nature of phone-hacking at the paper. He was one of the first former staffers to go on the record about the practice, and to reveal that he had hacked phone messages himself.
The News of the World's reaction to his claims in September 2010 was to attack him as an unreliable witness and to "reject absolutely any suggestion or assertion that the activities of Clive Goodman and Glenn Mulcaire, at the time of their arrest, were part of a 'culture' of wrongdoing".
Stuart Hoare said in his witness statement: "I have agreed to provide evidence to the inquiry because I feel that it is my duty and my promise to my younger brother to uphold his name and finally prove that everything that Sean said was the whole truth.
"Sean did everything he was asked in the name of journalism, was applauded for it and then every door shut in his face. His character was then pulled apart. Sean was never allowed to re-enter the journalistic world that he lived for."
He added: "What has never been reported was the fact that Sean came from a very stable, close, loving and private family that had beliefs and focused on hard work and education."
He noted that Coroner Edward Thomas had this year said Sean Hoare had done "extremely well" in abstaining from alcohol, and did not drink for a year after being diagnosed with liver disease.
Hoare added: "Dut in December last year he began drinking again as he became caught up in the phone-hacking scandal".
He described his brother as a "a proper old school journalist, described by many as one of the most charismatic people you could ever meet. It is fair to say that Sean loved his job and lived for journalism."
He noted that Sean's decision to go public was not "motivated by money as he did not get a single penny for any of the articles written in the New York Times".
He said: "His sole motivation was based on trying to put wrongs right. Sean had worked with certain individuals at both the Sun and News International where phone-hacking was a daily routine.
"l know this to be the case because Sean and I regularly discussed this and there are emails in existence which support Sean's description of a practice referred to during such meetings as 'the dark side'.
"It wasn't until a close colleague was jailed and hung out out to dry that Sean realised that this individual was being used as a scapegoat to protect the management.
"I can't stress strongly enough how upset Sean was over this injustice. The reality was that phone-hacking was endemic within the News International group (specifically Sean identified that this process was initiated at the Sun and later transferred to the News of the World) and he went on record both verbally and in writing to make this claim."
Later on in his testimony, Hoare said: "Undoubtedly, one of the major issues during Sean's employment with the News of the World was that the newsdesk was out of control and that stories were obtained with ittle or no ethics because of the pressure put on journalists to deliver. There were also monetary rewards that motivated some indivudals to fabricate and embellish stories that would sell newspapers."
Hoare said that his brother had "a wide and loyal circle of friends who will miss him but his real legacy should be the courage and conviction he showed in speaking out about he News International phone-hacking scandal."
In spoken testimony this morning, Hoare said that his brother also outlined how News of the World journalists were involved in the process of "pinging" - using confidential mobile phone data to establish an individual's location.
He described it as "a way to track people through their mobile phone, like gps or google maps, they would pass a phone number to someone and then get the exact position". Hoare said that according to his brother "it was clear it was a police officer" who was providing the information.
Sean Hoare was in regular contact with deputy editor of The Independent on Sunday James Hanning.
Hanning told the inquiry today that he was told by Hoare that "Blagging and fishing expeditions were standard practice, Sean would often hear 'we haven't written about x in a while, dig around and see what you can get'."
Hoare also apparently told Hanning that he "and another employee would pay employees at other papers for their newslist. There was a certain amount of cash in the office for that reason."