O'Donnell, a single mother motivated partly by her desire to spare her daughter the trauma of watching her die painfully, was prominent among the activists who campaigned for the bill signed into law last year. It will make it legal for the terminally ill to seek medical aid to die.
She died — as she thought she would — before the law's anticipated enactment later this year, according to a statement released by the advocacy group Compassion and Choices.
A Valencia resident, O'Donnell continued traveling and giving interviews in support of the bill as her Stage 4 lung cancer spread throughout her body and her illness grew dire.
T. Katz, afternoon drive-time hostess on Santa Clarita Valley's KHTS-AM (1220), said it was clear O'Donnell was suffering in the studio during on-air interviews at the station as the campaign waged on.
"She was very uncomfortable and — because she was morphine intolerant — there was nothing she could do to make herself feel better. That was part of her drive to do what she did," Katz said.
O'Donnell spoke explicitly of her sufferings to KHTS listeners, and in public statements. "The pain is pretty significant now," she told Katz in one interview. She said Percocet was her last-ditch option, but "I take a lot of it and it barely takes the edge off the pain."
O'Donnell was born July 24, 1968, according to the Compassion and Choices statement. She attended law school while working as a police officer, and was admitted to the state bar in 2003. She had been promoted to sergeant and detective before shifting to teaching, and then to legal practice.
She was tall — 6-foot-1 — with auburn hair, and cut a striking figure in courtrooms where her composure under pressure made her a proficient lawyer, said colleague Steve Harber, partner with the McCune & Harber law firm of Los Angeles, which represents, among others, the city and county, and local police and firefighters.
O'Donnell joined the firm in 2009, Harber said, after one of its attorneys described struggling in a trial.
"He said there was this attorney on the other side who was just great and was giving him fits," Harber recalled. The attorney in question was O'Donnell, who proved so good — and so problematic for their case — they decided to hire her, he said.
O'Donnell became one of six partners in the firm, and specialized in employment cases involving firefighters. She remained until her worsening condition made it difficult for her to shoulder a full load. But she carried on her advocacy work.
On her travels, O'Donnell was often accompanied by her daughter, Bailey Donorovich, 21, who also appeared by her side in interviews.
O'Donnell dreaded the possibility that her illness and impending death would cause the young woman distress, Harber said.
She saw to the practical details, he said, compiling a large binder for her daughter labeled "When I Die." It had tabs for subjects such as the family insurance, and how the mortgage worked — "Everything she needs to know," he said. But O'Donnell remained worried that, if she lingered in great pain, "her daughter would just see her suffering, day by day," Harber said.
She told him, "I'm afraid, but I am really afraid of my daughter going through that," he said.
O'Donnell filed a lawsuit in a state court last year seeking legal access to life-ending drugs for terminally-ill Californians. She also testified before legislators, and spoke one-on-one with a top advisor to Gov. Jerry Brown in the days before he signed the bill.
Opposed by religious groups and advocates for people with disabilities, the California law will permit physicians to provide lethal prescriptions to mentally competent adults who have been diagnosed with a terminal illness, and are expected to die within six months. It is slated to take effect 90 days after a planned legislative special session later this year. O'Donnell died Saturday, her colleagues confirmed.
Described as a devout Christian and lifelong Republican, O'Donnell had said she did not want to be a law-breaker. In interviews, she characterized the right-to-die campaign as a civil rights movement, and framed it in terms of individual choice.
"Even if there is one person, just one, in the state of California that needs this and wants this, this should become law," she said.
She seemed particularly intent on reaching those of her own political bent. Harber, for example, said he was struck at how O'Donnell sought to explain her motivations to him, rather than avoid the potentially controversial topic.
"As a Christian Republican, I'm not even sure how I feel," he said. But hearing O'Donnell's concerns for her daughter, "I could understand and respect that," he said.
I think I'm going to think about her every day for the rest of my life," he added.
The Associated Press contributed to this report.