She was popular in Broadway theatre in her youth and was long noted as a suspect in the murder of Hollywood director William Desmond Taylor.

Shelby was widely mentioned as a suspect in the murder of Hollywood director William Desmond Taylor, whom she incorrectly believed was involved romantically with her daughter Mary Miles Minter (born Juliet Reilly).

[citation needed] The Taylor murder was followed by sensationalized and often fabricated newspaper reports which fed years of scandal.

Shelby was acquainted socially with the Los Angeles county district attorney and spent many years in Europe, both to escape the efforts of his successor to question her and avoid much adverse press attention.

In 1999, it was reported that in 1964 actress Margaret Gibson made a deathbed confession to Taylor's murder; however no independent confirmation has emerged.