Sir Mo Farah has explained how he came to change his account when questioned in 2015 about taking supplement L-carnitine before the 2014 London Marathon.
A BBC Panorama documentary aired last Monday revealed that Farah was interviewed by investigators from the US Anti-Doping Agency (USADA) in 2015 as part of its probe into his former coach Alberto Salazar and asked whether he had been given L-carnitine before the previous year's London Marathon.
Farah was tested six days after that race and the BBC reported that, despite listing a number of other products and medicines, he failed to record L-carnitine on his doping control form.
In transcripts obtained by the BBC, Farah denies having been given the injection in the initial 2015 interview with USADA.
Panorama reported he then met with UK Athletics' head of distance running Barry Fudge immediately after the interview and returned to the interview room as the investigators were preparing to leave.
At this point, Farah, who won 5,000 metres and 10,000m golds at the 2012 and 2016 Olympic Games, told them he had been given the injection.
In an interview with the Sunday Mirror, Farah explains: "I was questioned for five hours. I said one thing and then other things got said and now it's made out like I've done wrong, but if you know how it happened then it's easier to understand.
"When I came out I said to Barry, 'Hey mate, they kept asking me about this supplement. What's that?'
"He said, 'Yeah, it's this, you did take it', so I went straight back in and told them.
"I forgot, but as soon as I was told I ran back in. If I was a liar, why would I go straight back in? I said, 'Look, I genuinely forgot, I didn't know that. Now I do'."
Farah explained when he was questioned by investigators he thought he had only been given magnesium injections.
"I was 100 per cent convinced I hadn't taken it (L-carnitine)," Farah said.
"In my mind I hadn't taken anything else apart from magnesium. I put magnesium on the doping control form.
"I can sleep at night knowing I've done nothing wrong.
"I love representing my country, making my country proud and doing what I do best because it is a gift and that's why I do it with a smile. But it's not fair what comes with it.
"It's not fair on my kids and my family. It's just not right. It's depressing. Mentally and physically it's had an effect on me."
Excerpts from a legal letter from Farah's lawyers to the BBC, which have been seen by the PA news agency, read: "Mr Farah understood the question one way and as soon as he left the room he asked Mr Fudge and immediately returned... to clarify and it is plain the investigators were comfortable with this explanation.
"It is not against (World Anti-Doping Agency) rules to take L-carnitine as a supplement within the right quantities.
"Mr Farah... is one of the most tested athletes in the UK, if not the world, and has been required to fill in numerous doping forms.
"He is a human being and not a robot. That is relevant... if in fact something was missed from the form. Interviews are not memory tests."
Farah finished eighth in the 2014 London Marathon and the fact he had been given L-carnitine was first reported by the Sunday Times three years later.
L-carnitine is a naturally occurring amino acid that some studies suggest could boost athletic performance if it is injected directly into the bloodstream.
L-carnitine is not a prohibited substance under WADA rules. Injections and infusions of it were permitted within WADA rules in 2014 provided the volume was below 50 millilitres every six hours. The permitted volume is now 100ml every 12 hours.
Salazar, Farah's former coach at the Nike Oregon Project, was handed a four-year ban by USADA in October last year for doping violations, though he has appealed to the Court of Arbitration for Sport.
Farah, who ended his relationship with the American in 2017, has never failed a drugs test and is not accused of any wrongdoing.