In an emotional letter posted to social media on Tuesday morning, Moy wrote: "My days of serving as an elected official in our hometown ends today. I am at peace with being a private citizen of Fairfield."
Fairfield spokesperson Bill Way confirmed that Moy's resignation was submitted.
"At the moment, we don't have a comment yet until we get all the information together," Way said.
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Vice Mayor Pam Bertani will be assuming the role, wrote Moy, becoming the city's first African American mayor.
Attorney Gary Winuk was hired by Fairfield City Council members in November to investigate whether Moy "meets the residency requirements articulated under state law to remain eligible to continue her term as mayor."
Moy stated in her resignation announcement that she and her family have "suffered extreme duress and discrimination" because of the investigation, prompting her decision to leave office.
Moy also alleged the investigation led to her defeat at the polls on June 2, when she lost to incumbent Wanda Williams for the seat of Solano County supervisor for District 3, which encompasses a majority of Fairfield, parts of Suisun City and Travis Air Force Base.
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Winuk's report, issued to the council in March, was released to the public in May, and concluded that there was insufficient evidence to claim Moy was not a Fairfield resident, adding that continuing the investigation would be at the City Council's discretion.
To date, legal fees for the investigation have amounted to $66,170, paid out of the city's general fund. All six city councilmembers called for the investigation in November after fielding complaints from "a lot of people coming to the dais claiming (Moy) wasn't in city limits," City Councilmember Doug Carr said in a phone call.
Moy's announcement comes just hours before a special meeting Tuesday to determine whether the City Council would continue with the investigation into Moy's legal residency or not.
In emails, Moy claimed the investigation "always was and remains a setup."
She has stated that the attempt to remove her was partly due to her vocal opposition to California Forever, a massive, venture capitalist-backed real estate development planned for southeast Solano County.
In her letter, Moy addressed recent events in Fairfield, over which she has received criticism at recent council meetings.
"As you know, over the past few weeks, Fairfield has suffered horrific loss, turmoil, and currently mourns the life of Jamario Baker, while we pray for other victims of the shooting at Sem Yeto's graduation," she wrote.
"When a fight broke out at Fairfield High School on May 20, 2026, officers responded. Videos from that incident went viral. People, including me, were emotionally shaken, and had many questions. We still do," Moy wrote.