The parents of 18-year-old Buffalo shooting suspect Payton Gendron were interviewed by FBI agents over the weekend, police said.
On Sunday, Buffalo police commissioner Joseph Gramaglia said investigators including FBI agents and New York State troopers had been to Mr Gendron’s family home, where they interviewed his parents.
While details remain few and far between, Mr Gramaglia said both of Mr Gendron’s parents were cooperating with authorities.
The police commissioner also believed they were “absolutely distraught and devastated” by their son’s arrest in connection with the shooting at Tops Friendly Market on Saturday, Fox News reported.
Police believe the suspect gunman acted alone when he shot 10 people dead at the supermarket in Buffalo, about 200 miles away from his home in Conklin, New York.
Four people were allegedly shot in the parking area before Mr Gendron, dressed in military gear, continued to shot inside the store. Almost all of his victims were Black, authorities said.
He has since been charged with first degree murder and pleaded not guilty, while investigators have released details about his alleged motives for the attack on the predominantly Black neighbourhood.
Reports suggest he wrote a manifesto online contains white supremacist and nationalist themes, including ideas around “white replacement theory”. Video meanwhile showed his weapon – reportedly illegally modified – with white supremacist symbols.
“It is my sincere hope that this individual, this white supremacist who just perpetrated a hate crime on an innocent community, will spend the rest of his days behind bars. And heaven help him in the next world as well,” said New York governor Kathy Hochul on Sunday.
US President Joe Biden said in a statement that he and the First Lady were praying for the victims and their families.
He said: “We still need to learn more about the motivation for today’s shooting as law enforcement does its work, but we don’t need anything else to state a clear moral truth: A racially motivated hate crime is abhorrent to the very fabric of this nation.
“Any act of domestic terrorism, including an act perpetrated in the name of a repugnant white nationalist ideology, is antithetical to everything we stand for in America.”
Additional reporting by The Associated Press.