Martinez decided to run against the incumbent district attorney in 1996 while still a registered Democrat, like most voters in Doña Ana County. Local Republicans invited her and her husband, Chuck Franco, to lunch to discuss issues such as the death penalty, taxes and government spending. Martinez suspected they were on a recruiting mission.

“I remember telling my husband, ‘We’re going to be very polite. We’re going to say thank you very much and we’re going to leave,’ ” she said. Afterward, “We got in the car, we looked at each other and said, ‘Oh my God, we are Republicans! Now what do we do?’ ”

She switched her party registration, fully expecting to lose the election, but drew enough Democratic crossover votes to defeat her opponent. She handily won three reelection races — the last time running unopposed.

As district attorney, she was known for her tough prosecution of child abuse cases and crimes committed by illegal immigrants. During her gubernatorial campaign, she said she was opposed to tough Arizona-style immigration laws.