[2][5] An increase in the club's membership size came in turn with a series of violent attacks on law enforcement personnel, rival gang members, and local citizens.

The feud resulted in its first fatality on March 29, 1976 when Bruce Ritter was shot dead by a sniper while he was visiting the southeast Tucson residence of his brother-in-law, a Dirty Dozen member.

Expanded discussions took place the following day when two members each of the Dirty Dozen, the Seekers, the Devils Diciples, the Sons of Oden and the Soul Sinners met with authorities at the Pima County Sheriff's Department headquarters and "agreed to exercise control of their brothers so that these incidents stop".

[7] Howell and Kriley persisted in wearing their club's colors in the area, however, and they were summoned to a meeting with Dirty Dozen member Robert "Chico" Mora, who had been dispatched from Tucson, at a Globe roadhouse.

[4] Eleven Dirty Dozen bikers from the Phoenix area, including club president Gary "Greasy" Stacy, were subsequently arrested in connection with the killings by a contingent of local and state police.

Subsequently, the Mongols allied themselves with the Outlaws, who had established a presence in Tucson after the club's former Florida president James "Big Jim" Nolan moved to the city.

[6] In 1983, 44-year-old electrician John Turner was shot and killed by an unidentified individual when he attempted to use his pickup truck to run over a row of over twenty motorcycles belonging to Dirty Dozen members outside Gary's Lounge, a north Phoenix bar.

[19] One Dirty Dozen member, Charlie Prest, was allegedly handcuffed and beaten by off-duty police officers working as security at a David Allan Coe concert in Tempe on December 2, 1984, and two others claimed they were maced when they attempted to intercede.

[21] According to the indictments, the Dirty Dozen had conspired to take control of the methamphetamine trade in Arizona, and carried out counterintelligence operations against rival motorcycle gangs and law enforcement personnel.

[1][22] On March 27, 1986, Dirty Dozen associate Kenneth Dale Gann was arrested in Pima County as part of Operation One Percenter, a 12-month investigation by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) targeting motorcycle gangs.

[23] Operation One Percenter resulted in the arrests of 53 members and associates of 18 different biker gangs on various weapons and narcotics charges, during a series of raids in 18 U.S. states, and the seizure of 10 sawed-off shotguns, 10 machine guns, 63 rifles, 100 handguns, 4,500 rounds of ammunition, six silencers, a bomb, four hand grenades, five pounds of dynamite, 15 stolen vehicles, a stolen computer and a drug lab, as well as large quantities of cocaine, marijuana and PCP.

[5] On September 23, 1992, a 14-month investigation by a task force consisting of the DPS organized crime division, the FBI, the ATF, and the Phoenix and Mesa police departments culminated with over 400 law enforcement officers serving 68 search warrants on the residences of Dirty Dozen members in Maricopa, Pima, Yavapai and Pinal counties.

[2] The Dirty Dozen came to the attention of Sonny Barger, the reputed national leader of the Hells Angels, while he was serving a four-year sentence for conspiracy at FCI Phoenix in Arizona between 1989 and 1992.

[30] Robert Mora, the Dirty Dozen's Tucson chapter president, was credited with being responsible for the merger due to his incessant campaigning, as he sought a larger network of bikers to do business with.

[2] His role within the Arizona Hells Angels was reportedly an advisory position, as he did not hold officer status and he rarely attended rallies or public events.