A POLICE officer who ran an illegal gambling den was sent to jail yesterday for offering a colleague money in exchange for getting advance warning of raids. Constable Lai Po-keung, 24, pleaded guilty to offering an advantage and San Po Kong Magistrate Stephen Chow sentenced him to six months in prison. Lai was serving at Wong Tai Sin Police Station when he and others set up a gambling den in May last year. In June this year, Lai approached Detective Senior Constable Wong Wai-to who subsequently warned of an imminent raid. Lai offered him $4,000 for his services. Lai is helping the Independent Commission Against Corruption track down other officers who may have been involved in the scam.