Many people trace the origin of Paul Gascoigne's problems with addiction and mental health back to the afternoon of May 19th 1991.
After 15 minutes of the 1991 FA Cup final, Gascoigne launched into a wild, knee-high tackle on Nottingham Forest's Gary Charles.
The impact snapped Gazza's cruciate knee ligaments and he was never the same player, or arguably the same person, again.
His problems have been exhaustively documented in the media, unlike those of the victim of that wild tackle.
Charles's life has followed a tragically similar path to that of Gazza since that infamous tackle.
He has battled alcoholism and been to prison three times. When I searched for stories about him on the internet and in the newspaper cuttings library, there were plenty of stories about his court appearances, yet no word from the man himself.
This impression of a forgotten man was enhanced when I spoke to some of the people who had known him when he was a player, turning out for Nottingham Forest, Aston Villa and West Ham.
I spoke to some of his former team-mates and managers, the Professional Footballers' Association, the Football Association, his ex-agent, yet no-one had spoken to Charles for years.
They knew all about his problems, but had not even tried to get in touch with him. It seemed astonishing. After all, here was a man who had played for England three times, and who was universally described as a nice guy by those who had known him during his playing career.
So I decided to track him down. This proved a long and laborious process, but eventually I got his address, wrote him a letter, and was amazed when he called me.
After a few convivial conversations we arranged to meet at his home in Derbyshire. I was worried that he wouldn't be there, but he answered the door immediately.
The first thing that struck me was how good Charles looked, as you can see from the picture above. For someone who had abused his body with alcohol for so long, often drinking
himself into oblivion, he looked lithe, healthy and younger than his 38 years.
And during our five hours together, I found him to be frank, open and friendly. It was very difficult to believe that this was a man who had been found guilty of assaulting a woman in a taxi office in 2006 and of attacking a friend of his girlfriend a few years before that.
But that is the nature of alcoholism.
So what had he been doing recently? He was released from his third spell in prison - for breaking the terms of a suspended prison sentence by threatening a nightclub bouncer with an imaginary knife in Derby - last May.
Then he found a saviour in the form of his former Forest team-mate Roy Keane. The duo had lived together for a year when they were teenage trainees at Forest in the 1980s, but lost touch when Keane moved to Manchester United in 1993.
"Roy was absolutely brilliant to me," Charles told Undercover Sport. "I went to live with him and his family when I came out of prison and he invited me to train with the Sunderland lads.
"I went with them on their pre-season tour of Holland and had a great time. It reignited my enthusiasm for football and made me realise what I'd missed about the game, the banter with the other lads, the cameraderie."
Keane helped him to enrol on a coaching course in Wolverhampton, which he completed last summer.
But since then, he had been a little aimless. His time has mainly been taken up with rebuilding his fractured relationship with his three sons.
NEXT WEEK: SECOND INSTALMENT OF THE CHARLES INTERVIEW
