On 6 June 2020, gunmen killed 10 men at a drug rehabilitation center in Irapuato, Guanajuato, Mexico. Less than a month later, on the afternoon of 1 July 2020, a second and far deadlier attack occurred at an unregistered detoxification center called "Buscando el Camino a mi Recuperación" on Lerdo Street. Around 5:45 p.m., at least three armed men arrived in a red vehicle, entered the two-story building, threatened women on the ground floor, then went upstairs, broke down a door, and forced male patients to lie down before shooting them. They returned downstairs and shot three more men, wounding three women, before fleeing. Twenty-four people died at the scene and seven were injured; four more victims later died in hospital, bringing the toll to 28 deaths and three injuries, later revised slightly to 27 deaths. All those killed were men; the wounded survivors were women.
These attacks occurred during a particularly violent period in Mexico's ongoing drug war, which has intensified since 2016. Guanajuato state, where Irapuato is located, was a site of intense conflict between the Jalisco New Generation Cartel and the Santa Rosa de Lima Cartel, especially after the arrest of relatives of Santa Rosa de Lima leader José Antonio Yépez "El Marro" on 20 June 2020 triggered a wave of reprisals. Irapuato itself had previously seen violence at detoxification centers, including a kidnapping in December 2019 and an arson in February 2020, and the city was ranked among the most dangerous in the world by homicide rate in 2019.
Investigators concluded the July 1 massacre was linked to the cartel territorial war. On 5 July 2020, a Reaction and Intervention Task Force arrested three suspects, identified through ballistics, witness interviews, and video surveillance analysis. On 6 July, the Guanajuato General Prosecutor's Office stated the suspects belonged to a local criminal group in the Laja-Bajío area allied with the Santa Rosa de Lima Cartel, and that the attack was allegedly ordered by "El Marro." Authorities also sought a man known as "El Muletas," an alleged Jalisco New Generation Cartel member suspected of involvement without direct participation.
On 13 July 2020, the suspects appeared before a judge. One, Jesús Emmanuel Quezada Martínez, was charged with aggravated homicide of 27 people and six attempted homicides; the other two were charged with illegal weapons possession and crimes against health. All three were held in pre-trial detention.
Following the massacre, the Guanajuato government said it would identify state detoxification centers to establish security measures. On 16 July 2020, President Andrés Manuel López Obrador and Guanajuato Governor Diego Sinhue Rodríguez Vallejo agreed to cooperate against insecurity. Cartel lieutenant José Guadalupe "El Mamey" was arrested on 24 July 2020, and "El Marro" was captured by the Mexican Army on 2 August 2020, though his arrest warrant cited fuel theft and organized crime rather than the massacre specifically. By October 2020, officials reported the Santa Rosa de Lima Cartel had fragmented into smaller competing groups.