Watson had acquired homestead rights on land with water resources vital to the wealthiest rancher in the county, Albert Bothwell, when she was accused by him of cattle rustling.

The bodies were left hanging for two days, and the reputation that attached to her until recently was quickly established by newspaper publicity.

[1] It is likely that she was the daughter of Thomas Lewis Watson and Francis Close, who married the next year on May 15, 1861, in Grey County, Ontario.

[1] The eldest of ten surviving children, Watson helped at home and attended school, learning to read and write in a small one-room building.

It was unusual during that period in American history for a woman to move independently and alone, but she found work as a seamstress and a cook.

[6][4][5] On February 24, 1886, Watson met James "Jim" Averell, who was in Rawlins to file a homestead claim for land along the Sweetwater River, about 1 mile (1.6 km) from the Oregon, Mormon, and California Trails.

In 1872, about two dozen of the cattlemen with the largest ranches banded together to create the Wyoming Stock Growers Association (WSGA) to protect their rights to the open range.

[15][16] Forty-one cattle were branded, a relatively high number considering the year before she had purchased only 28, all specifically described as being in poor health.

[17] In a move that may have been retaliation for the repeated denial of her brand applications, Watson filed for approval to construct a water ditch to irrigate more of her land.

On July 20, 1889, a range detective, George Henderson, was cited by Bothwell in a meeting with other ranchers as having seen that Watson had rustled cattle.

[5] Watched by Gene Crowder, Bothwell and those ranchers he had convinced to go along with him arrived on the ranch with a buckboard and told Ella at gunpoint to get on it or be shot as they were arresting her for rustling and taking her to Rawlins.

By the time Buchanan reached where they had stopped, Bothwell was stringing up a rope, and one of his men putting a noose around her neck.

[4][5] Although the events caused a political controversy in the state, Bothwell acquired both homesteads of the murdered victims and ran his ranch without any legal repercussion or other retribution until he retired to Los Angeles, where he died in the 1920s.

[citation needed] Her death, and that of Averell, "became symbols of the societal contempt raging against rustlers during the latter part of the nineteenth century.

"[21] The Cattle Kate myth was largely accepted until the late 20th century, when composer George Hufsmith began researching Watson's life for an opera, The Lynching of Sweetwater.

Maureen O'Hara played a madam who inadvertently helped Averell (William Bishop) run a cattle rustling empire.

Heaven's Gate, directed by Michael Cimino and starring Kris Kristofferson and Isabelle Huppert, was "one of the most costly films ever made - and one of Hollywood's biggest box office failures".

[25] Watson's story appears in Red Light Women of the Rocky Mountain by Jan MacKell and includes an illustration of her made by Herndon Davis.