Arno Conklin was a District Attorney in Los Angeles. In 1953, he successfully prosecuted a woman who had poisoned both of her parents, asking for and receiving the death penalty against the killer. By the mid-1950s, Conklin had ascended to the position of Senior Deputy District Attorney, and by the late-1950s, he had become an Assistant District Attorney.
Before 1961, Conklin was introduced to Marjorie Lowe by Johnny Fox, who Conklin believed was a "businessman." On 17 March 1961, he attended the Hollywood Masonic Lodge's St. Patrick's Day Dance with Lowe, Fox, and Meredith Roman, and was photographed with them by Boris Lugavere. Before October of 1961, Conklin had fallen in love with Lowe, and she admitted to him that she was a prostitute.
On 27 October 1961, Conklin made the decision to sacrifice his career, and he and Lowe met to make arrangements to get married in Las Vegas the next day. Conklin called his campaign manager Gordon Mittel to request Mittel stand as his best-man, but Mittel declined, insisting that marrying Lowe would destroy Conklin's career. When Lowe was found dead the next morning, Conklin was devastated, and instructed Mittel to investigate Fox, whose alibi was confirmed. On 5 November 1961, Conklin called LAPD vice detective Claude Eno regarding Lowe's murder, and agreed to allow Fox to be interviewed provided that he and Mittel be present.
On 1 February 1962, he announced that he intended to run for the position of District Attorney being vacated by retiring D.A. John Stock, with Mittel running his campaign. In September of 1962, his connection to Fox was discovered by Times journalist Monte Kim, who was subsequently offered a position as Conklin's press spokesman by Mittel in exchange for Kim's cooperation in rewriting a story concerning Fox's death to hide the pimp's past. Conklin was mentioned in the Times article announcing Fox's death on 30 September 1962. In November of 1962, Conklin was listed as the Treasurer of McCage Inc., a shell corporation through which monthly payments of $1,000 were routed to an account owned by Detective Eno.
In the mid-1960s, Conklin hired Roger Goff as a prosecutor.
In 1968, Conklin was poised to make a run for the office of the Attorney General, but chose not to run after receiving information suggesting that Mittel had been responsible for Lowe's death. He returned to private practice, founding a one-man firm and taking nearly 60% of his caseload on a pro bono basis. At some point between 1968 and the early 1990s, Conklin lost both of his legs to diabetes, and became confined to a wheelchair with prosthetic leg attachments. He also established the Arno Conklin Award, which was given to the administrative prosecutor of the year at the annual prosecutors banquet.
In April of 1994, Conklin received a visit at his retirement home by LAPD detective Harry Bosch, the son of Marjorie Lowe and criminal defense attorney J. Michael Haller. Bosch believed that Conklin had either killed Lowe or knew who did. Conklin confessed that while he hadn't done so directly, he had long felt that his own actions had resulted in her death, specifically his protection of Mittel. Conklin explained Mittel's involvement in the attorney's career, stating that he believed Mittel had killed Lowe. Bosch left to confront Mittel.