One of his accomplishments was to help (along with his associate James Hume) identify Charles E. Boles as the perpetrator of the Black Bart stagecoach robberies.
Other notable early California outlaws he helped bring to justice include Bartolo Sepulveda, Narrato Ponce, "Red-Handed Procopio, and Juan Soto.
He tracked the Tiburcio Vasquez gang for two months and 2700 miles, finally locating him in an adobe house in what is now West Hollywood.
Morse provided the tip to Los Angeles County Sheriff Billy Rowland, whose posse captured Vasquez in 1874.
He investigated San Francisco's Dupont Street Frauds case of the 1880s, exposing the corruption of the city's mayor, Andrew J. Bryant.