'I still don't know why I did it.' Marine A on the 2011 killing, his life after jail and a possible film

• Video report by ITV News Correspondent Rebecca Barry

The Royal Marine who was jailed for killing an injured Taliban fighter in Afghanistan has said: "I still don't know why I did it."

Alexander Blackman, 42, known as Marine A, said the killing in 2011 was "not exactly the proudest moment of my life" in his first TV interview since being released from prison 12 days ago.

Speaking alongside Claire Blackman, who he has described as his "wife in a million" after she led a tireless public campaign calling for her husband's release, Mr Blackman said he has received "lots of kind offers of employment" since being released which he would consider in time.

And the couple refused to rule out the possibility of holding future talks over turning his story into a Hollywood film.

"Nothing is ruled in and nothing is ruled out," Mrs Blackman said. "It's a fun conversation to have probably but we haven't gone there yet."

The former sergeant had spent more than three years in jail after being convicted of murdering an injured Taliban fighter in Afghanistan in 2011.

Following an appeal, judges reduced his life sentence in March to seven years for diminished responsibility manslaughter, prompting his release late last month because of time already served.

Addressing the killing, Mr Blackman said he still couldn't explain what he regards as a "moment of madness" during the "hardest tour I'd done".

"I really couldn't tell you (why I did it)," he said. "I haven't got a definitive answer."

Mrs Blackman said it was not for her to "judge" her husband's actions but said: "I feel personally, fairly certain, that if he had a time machine and could go back and do things differently, he absolutely would."

Mr Blackman's conviction came after video footage recorded on a camera mounted to the helmet of another Royal Marine captured the moment he shot the insurgent.

He said the "five-minute" footage was a misleading representation of an incident that took around an hour to play out.

"You can put quite a few different spins on what was said," he said. "Unless you were there you don't know the full story."

The commando was "dismissed with disgrace" from the Royal Marines after serving for distinction for 15 years before being jailed in 2013.

Asked if he felt the military had hung him out to dry after the incident, Mr Blackman said he did not know the "facts and figures of what went on" and so would not apportion any blame.

Mr Blackman said being home was a "really good feeling" and he had found it "surprisingly easy" to readjust to civilian life after his release, while Mrs Blackman said it was "wonderful" to have her husband home.

He said he had been preoccupied by "simple day-to-day trivia", like registering to vote and getting his phone "sorted out", and was still to decide on his future.

"I've had lots of kind offers of employment. Once things have quietened down I'll take a look," he said.

Mr Blackman's jail term ended shortly after the appeal court accepted the grounds of diminished responsibility as he was suffering from an undiagnosed mental illness, known as adjustment disorder.

A Royal Navy review found warning signs showing Marine A's unit were suffering from "psychological strain and fatigue" were missed by senior officers in Afghanistan.

The former sergeant later said he believed the fighter was already dead and he was merely taking his anger out on a corpse.

It was argued during his appeal that Sergeant Blackman and his men had been overstretched and under resourced during his tour of duty in Helmand in 2011.

"It was arguably for me the hardest tour I'd done," Mr Blackman said.