Who are the four Pakistan players named by the News of the World over spot-fixing allegations? And who was the fixer?
BBC Sport profiles the key figures in the events that have rocked cricket to its core.
Still only 18, during day two of the fourth Test against England at Lord's in August 2010 the left-arm paceman became the youngest bowler in Test history to take 50 wickets.
He went on to take his best Test figures, picking up 6-84 in England's only innings, and was ranked the eighth-best bowler in Test cricket at the time of the scandal.
He made both his Test and one-day debuts in July 2009 and has gone on to snare 51 Test wickets at a shade over 29 runs apiece, and has a further 25 victims in one-day internationals.
Born in Gujjar Khan, Punjab, he has a whippy action that enables him to swing the ball both ways at a lively pace that can touch 90mph.
Of the three no-balls bowled which led to the investigation, Amir is alleged to have bowled two of them, one on Thursday and one on Friday of the fourth Test.
A controversial figure who has twice been suspended after testing positive for banned substances - although one ban was subsequently overturned - and who was also detained in Dubai for suspected possession of illegal drugs.
He is a fine swing bowler who can manipulate the ball sufficiently at no more than medium pace - he says "pace is nothing" - to remove the very best at Test level.
Although he could bowl quicker he is happy to hover about the 80mph mark and his guile and ability to move the ball both ways have brought him 106 Test wickets at an average of 24.36.
The 28-year-old made his Test debut in 2005 and was ranked third in the ICC bowling rankings during the Test series against England.
He is alleged to have bowled one of the three no-balls in question on Thursday, the first day of the Test at Lord's.
The 26-year-old was only appointed Pakistan's Test captain in July 2010 and succeeded Shahid Afridi, who stepped down from the role after a single game in charge following a defeat in the first game of their two-Test series against Australia in 2010.
Butt had previously been appointed vice-captain at the beginning of the tour after a number of senior players were discarded following what turned out to be a disastrous trip down under.
A stylish if inconsistent left-hander, who averages 30.43 from 30 Tests, he has proved more successful in ODIs, scoring 2,725 runs at an average of 36.82, including eight centuries.
He made his debut back in 2003 but was in and out of the side for several years until nailing down a regular place in 2007.
Along with Amir and Asif, Butt has had his telephone taken away by police but he said: "These are just allegations and anybody can stand out and say anything about you, it doesn't make them true."
Mazhar Majeed, the man at the centre of the spot-fixing controversy, is a UK-based property tycoon.
With his brother and business partner Azhar Majeed he claims to manage several of Pakistan's leading players and have contacts with senior figures in the Pakistan Cricket Board.
This close relationship between Majeed and the players appears to have concerned Pakistani authorities and at the start of the tour the players were told they were no longer allowed to have agents in their hotel rooms.
Mazhar Majeed, along with his wife and another man, were arrested by customs officers on Tuesday over claims he has laundered tens of millions of pounds through non-League football club Croydon Athletic.
South African Haroon Lorgat was appointed chief executive of the International Cricket Council in April 2008, replacing Australian Malcolm Speed.
Lorgat, a businessman and chartered accountant, was an all-rounder for Eastern Province and Transvaal and was a national selector from 2001 to 2003, going on to chair that panel from 2004 to 2007.
Lorgat has defended the ICC's Anti-Corruption and Security Unit (ACSU) in light of the scandal, pointing out the body lacks the powers available to conventional law enforcement agencies.
The ACSU was set up in 2001, in response to the Hansie Cronje match-fixing scandal, as a means of establishing and publicising anti-corruption and security measures for players, support staff and administrators.