"[3] In 1942, attorney George Shibley retained McGrath to assist in his defense of 22 Mexican American youths accused in the Sleepy Lagoon Murder, the largest mass trial in California history.

The youths, aged 17 to 21, were accused of killing a Mexican farmworker near a swimming hole in a section of southeast Los Angeles County then known as Sleepy Lagoon.

[4] McGrath was recovering from a bout of pleurisy, and Shibley brought her the transcript of the trial to summarize each day's testimony.

During the 13-week trial, the judge did not allow the defendants to confer with counsel and refused to let them cut their hair or receive fresh clothing.

Working with Carey McWilliams, McGrath published a newsletter, spoke in public about the cause, and raised money to support an appeal of the convictions.

The committee's supporters included Orson Welles, Rita Hayworth, Nat King Cole, and Anthony Quinn.

[1] While McGrath was working for the Sleepy Lagoon Defense Committee, the group was charged with being a Communist-front organization, and the FBI conducted surveillance of its members.

McGrath was the one who sent the telegram to San Quentin informing the Sleepy Lagoon defendants of the successful appeal.

[1] In 1981, McGrath told a Los Angeles Times interviewer that Sleepy Lagoon appeal was "the most important event in my life.

[3] Actress Tyne Daly played the part of "Alice Bloomfield" (based on McGrath) in the motion picture.

"[4] McGrath's role in the events was also depicted in the film "Zoot Soot Riots" broadcast on PBS as part of the "American Experience" series.

In 1986, after learning that the local bar association had no pro bono program, she offered to start one and for two years she was a full-time volunteer, working with attorneys and court personnel as a client advocate.

[2][4] McGrath held jobs as a publisher's sales representative, production manager for an art film, retail clerk, figure model, and teacher of self-defense for women.

[9] McGrath's papers, including correspondence with the Sleepy Lagoon defendants, have been donated to UCLA and are available through the Online Archive of California.