The most accepted hypothesis about the Keddie murders involves a complex love triangle between Martin Smartt, his wife Marilyn, and Sue Sharp. The theory suggests that Martin and Sue were engaged in an affair and that Sue was advising Marilyn to leave Martin, whom she claimed was abusive. Upon discovering this, Martin supposedly conspired with Bo, a friend and alleged mob enforcer who had been staying with the Smartts just 10 days before the murders, to eliminate Sue.

This theory could explain why Marilyn left Martin on the day the murders were discovered. It also provides a possible reason for sparing the Smartt boy and the other Sharp boys in the adjacent room. Additionally, it lends some context to the handwritten note from Martin that Marilyn handed over to the Plumas County Sheriff's Department.

Some investigators, particularly those who revisited the case in 2013, believe the murders may be part of a broader conspiracy. Investigator Gamberg suspects that the Department of Justice and the Sheriff's Department under Doug Thomas might have been involved in a cover-up. He speculates that Bo and Martin were possibly part of a larger drug trafficking operation, potentially connected to the federal government.

Martin as a Drug Dealer and Bo's Connections to Crime Syndicates

Martin Smartt was recognized as a drug dealer, while Bo was linked to crime syndicates in Chicago with vested interests in drug distribution. This connection may shed light on why the Sacramento Department of Justice deployed two special agents from the organized crime unit, who were allegedly corrupt, rather than agents from the homicide department. This decision raises questions about the handling of the investigation and might explain why Martin and Bo appeared to receive leniency, allegedly being advised by Sheriff Thomas to leave town.