Orange County historian Jim Sleeper described Modesta as a "charming dark-eyed beauty of San Juan" who depended more on her beauty than her intelligence "to keep food on the table and a roof over her head." She was an extremely proud woman and felt her mother's rights were being trampled by the Santa Fe Railroad. She was very upset with the railroad, as she felt they had never paid for a right of way through her mother's land. The trains were dirty, noisy, and kept her chickens from laying eggs.

She decided to do something about it. Locals said it was only a clothesline across the tracks with her laundry; Santa Fe said it was a railroad tie. A railroad agent removed it before a train came. Four months later she was arrested and charged with "attempted obstruction of a train."

The jury tied in her first trial. In the second, rumors circulated that the attractive single woman was pregnant. In 1889, moral standards weighed heavily and the jury convicted her. She was sentenced to three years in San Quentin. Her attorney, George Hayford, appealed that his client was convicted on her reputation, not her deed. He was heard before the state Supreme Court, but lost on a technicality.

Modesta Avila died after serving two years of her sentence. She was 22 years old.