LONDON (AP) Jeff Rees is retiring after more than four years in charge of tennis' anti-corruption group, and former police officer Nigel Willerton will replace him on Jan. 1.

The Tennis Integrity Unit announced the changes Monday.

Rees was hired as Director of Integrity in August 2008 after helping review possible match-fixing in professional tennis.

The sport's governing bodies - the ATP and WTA tours, the International Tennis Federation and the Grand Slam Committee - formed the Tennis Integrity Unit after a series of player suspensions for betting on matches and a gambling investigation into a match involving Nikolay Davydenko.

During Rees' tenure, two players were banned for life from tennis.

Willerton has been an investigator for the Tennis Integrity Unit since June 2010.