Lei's life was consumed as usual by police work.  Unfortunately for Lei, his live-in girlfriend got fed up with Lei's workaholic lifestyle and dumped him in favor of Lei's assistant.  Ironically, the assistant acted as a liaison for Lei whenever she wanted to get in touch with him at work.  When Lei found out about this, he became extremely depressed.

Around the same time, Lei botched an operation to bring a crime syndicate to justice.  Lei failed to capture an agent of the syndicate who would have enabled the police to take down the syndicate's boss.  The failure cost the police force two years worth of intense undercover investigations.

Rival detectives who were jealous of Lei's stellar case record saw this as an opportunity to damage Lei's career.  Unbeknownst to Lei, the rivals reported to Lei's superiors that he botched the operation by "allowing personal affairs to affect his job performance."  As a result of this betrayal, Lei wound up on a one-month suspension from active duty.

Soon after his suspension, Lei learned from an informant that the syndicate was plotting to assassinate a boxer participating in The King of Iron Fist Tournament 4.  The syndicate apparently hired an assassin for the hit.

Lei thought that he could gain valuable information from the boxer about the syndicate.  If all went as planned, he could also capture the assassin and establish a plausible connection between the assassin and the syndicate.  Lei reasoned that this would aid efforts to bring the syndicate down.

Lei entered the Tournament with the hope of redeeming his honor.