[3] The first member of the Democratic Party to be elected Sheriff in 138 years, Villanueva campaigned as a reformer and appealed to some progressive values, but has received notoriety for more conservative policies during his tenure, as well as high levels of corruption.

[6] When Villanueva was nine years old, his family moved to Aguadilla, Puerto Rico, where he learned Spanish and walked to school while reading books along the rural back roads beside sugar cane fields.

[9] Villanueva joined the Los Angeles County Sheriff's Department in 1986 and eventually settled in La Habra Heights, California.

He was promoted to the rank of Sergeant, where he worked Lennox and Carson Sheriff Stations, the Community College Bureau, as well as the Advanced Officer Training unit.

Villanueva was promoted to the rank of Lieutenant and served at the Century Regional Detention Facility, which primarily houses female inmates.

Sheriff Lee Baca, Undersheriff Paul Tanaka, and numerous other department employees were caught in the scandal and were later convicted of various federal charges.

[23] In January 2021, California Attorney General Xavier Becerra launched a civil rights investigation of the LA County Sheriff's Department which sought to determine whether the LASD has engaged in a pattern or practice of unconstitutional policing, following allegations of excessive force, retaliation, and other misconduct.

[24] In 2022, a LASD commander filed legal papers accusing Villanueva of obstructing an investigation into a 2021 incident where a police deputy kneeled on a handcuffed inmate’s head, as well as retaliating against whistleblowers.

[28] Despite this, reports have surfaced from organizations like the RAND Corporation that deputy gangs persist, documenting at least four groups in the Sheriff's Department that still remain active as of 2021.

[32] In January 2020, former Los Angeles Lakers basketball player Kobe Bryant, his daughter Gianna, and seven others were killed in a helicopter crash in Calabasas, California.

County attorneys received a cease-and-desist letter from Southern California Gas that owned the property and had not given written consent for the grading and installation of the landing pad.

[40] Though the LASD was one of the first law enforcement agencies in the nation to test body-worn camera technology, prior sheriffs had failed to implement such a system.

[41] Villanueva directed the removal of federal immigration agents from Los Angeles County jails, court facilities, and patrol stations.

[42][43] During his 2018 campaign, Villanueva promised to end the "pipeline to deportation", which he described as being built upon the sheriff's department's cooperation and financial ties with federal immigration authorities.

[45] From 2005 to 2018, the Los Angeles County Sheriff's Department and Board of Supervisors accepted $122,189,627 from the United States Government in exchange for a database of inmates without proof of valid immigration status.

Villanueva suspended the department's participation in this program immediately after taking office, describing the cash payments as "blood money".

[46][47] On September 12, 2023 Villanueva announced his candidacy for the Los Angeles County Board of Supervisors, challenging incumbent Janice Hahn.