"The Group" is a name given to a group of six ex-police officers who are behind the missing $18 million from the Bank of Los Angeles Shootout and the framing of Charlie Crews on the Seybolt murders. They include Jack Reese, Mickey Rayborn, (possibly) James Dunn and three other unnamed members. The name "The Group" has never been addressed within the series. It is just a title generally adopted by the media outside the show. The number of people in this group has only been addressed once by an unidentified man as he relates a message from the other members of The Group to Reese, "You go back a long way, but, not for nothing. There was six, there is five, there could just as easily be four."
At the Bank of Los Angeles Shootout, Reese was the SWAT team leader in charge. He and his men stole the missing $18 million behind the scene.
Unknown to Charlie Crews, his friend Tom Seybolt was doing money laundering for The Group through the bar he and Crews own. When The Group found out Seybolt skimming, they killed him and his wife and son. Only his 9-year old daughter Rachel survived. They framed Crews for the murders and he was convicted and sent into prison for 12 years until proven innocent with DNA.
While Dunn was reported to be killed by an accidental gun discharge and believed to have actually commited suicide in 1988, the conversation between Jack Reese and the unidentified man seems to insinuate that Dunn was in fact killed by The Group.
Crews has a news cutting on James Dunn's funeral. There are 5 police officers in the article's photo. Reese is in the front, and the one on the left has been identified by Mrs. Dunn as Mickey Rayborn. The other three in the photo have not been recognized, and whether they are also the other three members of The Group is still unclear.
Rayborn reveals in Episode 2-15: I Heart Mom about the shootout, "That was just the start. We took a lot more over the next few years. That was the plan: Steal everything we could get our hands on, and then get out." He says Jack Reese's "crisis of faith came early. Jack never kept a dime, stayed a cop, gave his cash to charity." He also admits that Roman Nevikov is one of their "investments", yet they still have to put him away.
Jack Reese is revealed to have been killed at the hand of Roman Nevikov.