In November 1886, Slaughter was elected sheriff of Cochise County. Jim Milton, famous railroad detective, was tracking border smugglers in the area. He recalled Slaughter and the saga of the Jack Taylor Gang. "Four of Taylor's boys were still running loose after a train holdup in the Mexican state of Sonora," said Milton. "Their handles were Geronimo Miranda, Manuel Robles, Nieves Deron and Fred Federico. Mean scoundrels, they were wanted by the Mexican Rurales and Arizona authorities as well.
"...because they had kinfolk around Tombstone they had no more sense than to hide there, right under the nose of the law, which unfortunately for them, was John Slaughter."
Slaughter did make one big mistake in his career in law enforcement. He hired Burt Alvord as chief deputy. Even in later years, the mere mention of Alvord's name still infuriated John Slaughter. Alvord was a sidekick of a Slaughter ranch hand and sometimes lawman, Billie Hildreth. Hildreth recommended Alvord for the job. Slaughter knew Alvord sometimes ran with outlaws like Augustine Chacon, but he planned to use this to an advantage. It worked, although journalists chastised Slaughter for his choice of deputies. Alvord betrayed his friend, Chacon, to Captain Burton Mossman of the Arizona Rangers. Chacon was caught and hanged. Alvord then turned to a profitable career as a train and bank robber, and finally, he traveled to the West Indies and disappeared from history.
As his years rolled on Slaughter's health began to deteriorate. His feet would become so swollen that he would be forced to use crutches and wear slippers. He suffered from eczema on the hands and feet and would often have them bandaged. Later he suffered from high blood pressure. Finally, on Wednesday February 15, 1922 a doctor was called due to Slaughter's complaining of a bad headache. His wife found Slaughter dead in his sleep the next morning, he was 81. Attending his funeral was pallbearer James H. East, long time friend of Slaughter's and captor of Billy the Kid, and hundreds associates. He was put to rest in the Calvary Cemetery in Douglas, Arizona. His wife, Cora Viola Slaughter, lived another nineteen years, dying at age 80, on April 1, 1941, in Douglas, Arizona.