Andy Coulson, the former News of the World editor at the centre of the political row over allegations of phone hacking, was employed as David Cameron's director of communications between 2007 and 2011.
His appointment by the Conservative Party came months after he had quit the tabloid following the jailing of former NoW royal editor Clive Goodman and private investigator Glenn Mulcaire for hacking into the voicemails of Buckingham Palace aides.
Mr Coulson took up a similar role in Downing Street when Mr Cameron became prime minister in 2010, despite allegations about his knowledge of phone hacking while at the News of the World.
Mr Coulson resigned in January 2011 saying the continuing phone-hacking row was distracting him from his role. He was arrested on 8 July 2011 on suspicion of corruption and phone hacking, and was released on police bail until October.
David Cameron has repeatedly defended his appointment of Mr Coulson over the past two years.
9 July 2009
After reports the News of the World had been involved in the illegal hacking of up to 3,000 phones.
"It's wrong for newspapers to breach people's privacy with no justification. That is why Andy Coulson resigned as editor of the News of the World two and a half years ago.
"Of course I knew about that resignation before offering him the job. But I believe in giving people a second chance.
"As director of communications for the Conservatives, he does an excellent job in a proper, upright way at all times."
"No one is unsackable. But... we haven't had one single complaint about how he has done his job, or indeed about how the Downing Street press office has done its job.
"That is quite a contrast from the years of [Labour's director of communications] Alastair Campbell and [special adviser] Damian McBride and all the rest of them…
"He's someone who serves the government and actually runs a very good press office and communications department."
Mr Cameron was asked on BBC Radio 4's Today programme if it was true that Mr Coulson had offered his resignation:
"Obviously, when he was editor of the News of the World, bad things happened at that newspaper.
"I think there is a danger at the moment that he is effectively being punished twice for the same offence… I gave him a second chance."
When asked by John Humphrys: "Are you not concerned by what he had done in the past," Mr Cameron replied:
"Well, obviously I gave him a second chance. I think in life it is right to give someone a second chance. He resigned [for] what went wrong at the News of the World. I would just argue that, working for the government, I think he has done a good job for the government and for the country.
"He's extremely embarrassed by the endless publicity and speculation about what happened many years ago when he was editor of the News of the World... but he had a second chance from me to do this job and I think he's done the job in a very good way."
Speaking after Mr Coulson's resignation as director of communications at Number 10 Downing Street:
"I am very sorry that Andy Coulson has decided to resign as my director of communications, although I understand that the continuing pressures on him and his family mean that he feels compelled to do so.
"Andy has told me that the focus on him was impeding his ability to do his job and was starting to prove a distraction for the government. During his time working for me, Andy has carried out his role with complete professionalism."
Speaking after Mr Coulson's arrest:
"I decided to give him a second chance and no-one has raised serious concerns about how he did his job for me... But the second chance didn't work out.
"The decision to hire him was mine and mine alone and I take full responsibility for it. People will decide whether it is right to give someone a second chance or not. I do think it is right to judge an individual by the work he did for me.
"I accept he was an editor of a newspaper where some very bad things happened. Because he'd resigned... it was reasonable to offer him a second chance... People will judge me on that, and I fully understand that.
"When you work with someone for four years as I did and you work closely, you do build a friendship and I became friends with him... so, yes, he became a friend and is a friend."
David Cameron tells the Commons he hired Mr Coulson on the basis of "assurances" that he knew nothing about phone hacking while at News of the World:
"All these questions relate to the fact that I hired a tabloid editor. I did so on the basis of assurances he gave me that he did not know about the phone-hacking and he was not involved in criminality.
"He gave those self-same assurances to the police, to a select committee of this house and under oath to a court of law.
"If it turns out he lied, it won't just be that he shouldn't have been in government, it will be that he should be prosecuted.
"But I do believe, Mr Speaker, that we must stick to the principle that you are innocent until you are proven guilty."