A man looks a memorial for victims near the scene of a shooting at a TOPS supermarket in Buffalo, New York, U.S. May 15, 2022.
A man looks a memorial for victims near the scene of a shooting at a TOPS supermarket in Buffalo, New York, U.S. May 15, 2022. Reuters / BRENDAN MCDERMID

An investigation into the shooting of more than a dozen people in Buffalo, New York, turned on Monday to whether warning signs of the attack were missed, as public figures decried the suspect's racist ideology and the spread of white supremacy.

Authorities said Payton Gendron, 18, carried out an act of "racially motivated violent extremism" when he opened fire with a semi-automatic rifle on Saturday at the Tops Friendly Market in Buffalo, where 11 of the 13 struck were Black.

Investigators have said they are searching through phone records, computers and online postings, as well as physical evidence, as new details about the suspect's troubling past and meticulous planning emerge.

Those details included a Washington Post report on Monday that the suspect made a trip to the Tops store in March to map its layout in preparation for the attack. He was confronted there at the time by a store security guard, who thought he looked suspicious.

The newspaper said the planning trip to Buffalo was described in a 589-page document posted online by someone who identified himself as Gendron. The document is no longer available publicly, the Post reported.

The document referred to the Tops store as "attack area 1" and described two other nearby locations as attack areas to "shoot all blacks," the Post reported. Gendron counted that there were 53 Black people and six white people in the Tops at the time of his visit, according to the account.

Gendon's online postings also apparently included a 180-page manifesto that police are investigating. The manifesto outlined the "Great Replacement Theory," a racist conspiracy theory that white people were being replaced by minorities in the United States and elsewhere.

Investigators have said Gendron - who has been charged with murder and entered a not-guilty plea - was motivated by racism.

"The evidence that we have uncovered so far makes no mistake this is an absolute racist hate crime that will be prosecuted as a hate crime," Buffalo Police Commissioner Joseph Gramaglia told reporters on Sunday.

The Buffalo attack follows racially motivated mass murders in recent years, including the Atlanta spa shootings of March 2021, in which a white man killed eight people, targeting Asians, and a Pittsburgh synagogue attack in October 2018 that killed 11.

President Joe Biden and first lady Jill Biden plan to visit Buffalo on Tuesday.


At a news conference on Monday, attorney Ben Crump called on officials to define Saturday's attack as an "act of domestic terrorism."

"We can't sugarcoat it, we can't try to explain it away talking about mental illness. No, this was an act of domestic terrorism perpetrated by a young white supremacist," Crump said, surrounded by the weeping family of Ruth Whitfield, an 86-year-old woman who was slain.

Other victims included a pharmacist, a church deacon, a retired police officer who worked as a security guard at the store, and a young man who pushed grocery carts and did other jobs.

If the suspect had not been stopped, authorities said he planned to continue the killings, possibly targeting another large store nearby.

"He had plans to continue driving down Jefferson Ave. to shoot more Black people," Gramaglia, the police commissioner, told ABC News on Monday.

The teenager appeared on the radar of local law enforcement last June, when police detained him after he made a threat at his high school, Gramaglia told reporters. He was given a mental health evaluation and released after 1-1/2 days.

On Friday, almost a year later, Gendron made a several-hour drive from his home to Buffalo to undertake a final "reconnaissance" of the area, authorities said.

Authorities said that Gendron on Saturday, dressed in tactical gear, arrived at the Tops store and began his assault with the semi-automatic rifle, which he had bought legally but then modified. Law enforcement found an additional rifle and a shotgun in his car.

Gendron, who surrendered to police after the shooting, broadcast his attack on social media platform Twitch, a live video service owned by Amazon.com Inc. The video service said it removed the broadcast within minutes.