2017 Aztec High School shooting

On December 7, 2017, a school shooting occurred at Aztec High School in Aztec, New Mexico. William Edward Atchison, a 21-year-old former student, entered the school disguised as a student and hid in a second-floor bathroom. He was discovered by student Francisco "Paco" Fernandez, whom he shot and killed, before shooting and killing Casey Jordan Marquez in the hallway. Both victims were 17-year-old student-athletes. Atchison then walked through the halls firing randomly and attempted to enter a classroom where substitute teacher Katie Potter had barricaded 17 students behind a couch; he fired shots into the room through the wall but no one was hit. He then killed himself with a gunshot to the head at 8:16 a.m. School custodian Thomas "Emery" Hill was credited with alerting staff to the threat, and Potter's actions were credited by San Juan County Sheriff Ken Christensen with saving lives.

Atchison had a substantial online presence on neo-Nazi and white nationalist websites and had been investigated by the FBI in March 2016 after an online post about planning a mass shooting. The FBI closed the investigation after determining he did not own a firearm and after he convinced agents his statements were "trolling." In early 2016, Atchison had also been in direct contact with the eventual perpetrator of the July 2016 Munich shooting, which killed nine people. He legally purchased the 9mm Glock pistol used in the attack in November 2017.

The motive for the shooting is disputed. The Southern Poverty Law Center argued the attack was motivated by far-right extremism and linked it to a broader pattern of alt-right-associated violence, while the San Juan County Sheriff's Office, which completed its investigation in August 2018, concluded there was no evidence tying the shooting to Atchison's ideological views, instead attributing it to personal problems and a desire for notoriety. The sheriff's office also suggested Atchison may have chosen the date because it was the anniversary of the attack on Pearl Harbor.

In the aftermath, the community held vigils, and state and local officials, including New Mexico Governor Susana Martinez and U.S. Senator Martin Heinrich, made public statements. Marquez's mother later filed two wrongful death lawsuits: one against the Aztec school district and police department in December 2019, alleging failure to implement recommended security upgrades, and a second against the FBI in June 2020, alleging negligence in the FBI's 2016 threat assessment. The lawsuit against the FBI was dismissed with prejudice in December 2020 on grounds of federal immunity. Separately, German police faced criticism for a delay in sharing information about the Atchison-Sonboly connection with the investigating Bavarian authorities. In response to the shooting, New Mexico authorized additional funding for school safety infrastructure, and Aztec High School implemented new security measures including additional resource officers and hardened entrances.