[1] West Midlands police arrested Lee in February 2010 as part of an investigation into suspicious betting patterns at the 2009 UK Championship, but no further action was taken against him at that time.

After an independent tribunal found Lee guilty of influencing the outcome of seven matches in 2008 and 2009, he was banned from competing in or attending any WPBSA-affiliated tournament for 12 years, backdated to the beginning of his suspension.

His first ranking victory came at the Grand Prix, in 1998 defeating Dave Harold 6–4 in a hard-fought semi-final that saw Lee come from 3–0 and 4–1 down, before beating newcomer Marco Fu convincingly in the final, 9–2.

Due to a dip in form, at the 2006 Welsh Open he came to the competition outside the provisional Top 16 after failing to win a ranking tournament for four years.

[6] Following a heavy defeat by Joe Swail in the first round of the 2008 World Championship, confirming his drop out of the top 16 of the rankings, Lee considered retiring from the game.

[7] However, he did compete in the first ranking event of the 2008–09 season, the 2008 Northern Ireland Trophy, and after convincing wins over Judd Trump and Stephen Hendry, he reached the last 16, where despite making three century breaks he lost 4–5 to eventual runner-up Dave Harold.

On 11 February 2010 Lee was arrested by West Midlands Police on suspicion of cheating, in relation to an investigation by the Gambling Commission over suspicious betting patterns.

He lost in the first round of the 2011 UK Championship and in the German Masters reached his first semi-final since the 2006 Northern Ireland Trophy, but could not get past Ronnie O'Sullivan, who won 6–4.

[10] He then made it to the quarter-finals of the Welsh Open, where he was put off by a mobile phone ringing on his back-swing in a deciding frame against Ding Junhui and went on to lose the match.

[14] Lee's form in the second half of the season continued into the China Open as he registered his third ranking event semi-final of the year by defeating Judd Trump again, but could not feature in three successive finals as he lost 2–6 to Stephen Maguire.

[20] The following day—on his 38th birthday—Lee was suspended by the WPBSA following reports by at least two bookmakers of irregular betting patterns connected to the Premier League match, pending a full inquiry.

He was charged with violating sections 2.8 and 2.9 of the Members Rules and Regulations, which concern divulging information not already in the public domain with the express purpose of it being used for match-betting, and entering into an arrangement to influence the result of a game.

[25] On 10 April, the WPBSA announced that they would no longer be proceeding with the investigation into the Premier League match, although the inquiry into the remaining match-fixing charges would still go ahead.

[26] While suspended from WSA tournaments, Lee continued to compete in independently organised events, winning the RKGKhar Gymkhana Snooker Masters in May.

[27] The case was heard by independent tribunal, Sport Resolutions UK, in a three-day hearing chaired by Adam Lewis QC, starting on 9 September 2013.

[38][39] On 15 May, with Nicholas Stewart QC presiding, the remainder of the appeal was dismissed and the costs awarded against Lee at the Adam Lewis hearing were increased from £40,000 to £75,000.

Lee was charged with teaching snooker without a work permit and appeared in court on 14 April where he pleaded not guilty to breaching the conditions of his tourist visa.