Between October and December 1863, the rate of robberies and murders in and around Alder Gulch increased significantly, and the citizens of Virginia City grew increasingly suspicious of Plummer and his associates. Notable criminal acts by alleged members of the Plummer gang included: • On October 13, 1863, Lloyd Magruder was killed by road agent Chris Lowrie. Magruder was an Idaho merchant leaving Virginia City with $12,000 in gold dust from goods he had sold there. Several of the men he hired to accompany him back to
Lewiston, Idaho, were criminals. Four other men in his party were also murdered in camp—Charlie Allen, Robert Chalmers, Horace Chalmers and William Phillips—by Lowrie, Doc Howard, Jem Romaine and William Page. • On October 26, 1863, the Peabody and Caldwell's stage was robbed between the Rattlesnake Ranch and Bannack by two road agents believed to be Frank Parish and George Ives. Bill Bunton, the owner of the Rattlesnake Ranch who joined the stage at the ranch, was also complicit in the robbery. The road agents netted $2,800 in gold from the passengers and threatened them all with death if they talked about the robbery. On December 23, 1863, two days after the Ives trial, leading citizens of Virginia City and Bannack formed the Vigilance Committee of Alder Gulch in Virginia City. They included five Virginia City residents, led by Sanders. Between January 4 and February 3, 1864, the vigilantes arrested and
summarily executed at least 20 alleged members of Plummer's gang. Shortly after its formation, the Vigilance Committee dispatched a posse of men to search for Carter, Graves, and Bunton, known associates of Ives. The posse was led by Captain James Williams, the man who had investigated the Tiebolt murder. Near the Rattlesnake Ranch on the
Ruby River, the posse located Erastus "Red" Yeager and George Brown, both suspected road agents. While traveling under guard back to Virginia City, Yeager made a complete confession, naming the majority of the road agents in Plummer's gang, and Henry Plummer. The posse found Yeager and Brown guilty and hanged them from a tree on the Lorrain's Ranch on the Ruby River. On January 6, 1864, vigilante Captain Nick Wall and Ben Peabody captured Wagner on the Salt Lake City trail. The vigilantes transported Wagner to Bannack, where he was hanged on January 11, 1864. By this time, Yeager's confession had mobilized vigilantes against Plummer and his key associates, deputies Buck Stinson and Ned Ray. Plummer, Stinson, and Ray were arrested on the morning of January 10, 1864, and summarily hanged. The two youngest members of the gang were said to be spared. One was sent back to Bannack to tell the rest to get out of the area, and the other was sent ahead to Lewiston to warn gang members to leave that town. (Lewiston was the connection from the territory to the world, as it had river steamboats that traveled to the coast at
Astoria, Oregon, via the
Snake and
Columbia rivers.) Plummer was known to have traveled to Lewiston during the time when he was an elected official in Bannack. The hotel registry records with his signature during this period have been preserved. The large-scale robberies of gold shipments by gangs ended with Plummer's and the alleged gang members' deaths. Gang member
Clubfoot George was hanged at about the same time with Plummer. ==Posthumous trial==