A New Mexico man convinced the FBI he was not a threat. Then he carried out a school shooting.

Atchison, 21, said he was “plotting [a] mass shooting” and looking for “weapons that are good for killing a lot of people within a budget.”But “I’m not the type to actually do any of this stuff,” Atchison told the agents, according to a recording of the interview obtained exclusively by NBC News. It was one of 50 school shootings in 2017.An NBC News examination of the Aztec High School shooting — including a review of government records and an audio recording of an FBI interview of the future shooter — found a series of missed opportunities that point to what some experts say are nationwide shortcomings in how authorities assess and respond to potentially violent domestic extremists.The missed signals in the case echo what happened before the school shootings in Parkland, Florida, when the FBI failed to act on tips about the shooter, and in Oxford, Michigan, where school officials are accused of ignoring obvious warning signs.“This is yet another example of system failure,” said James Densley, an expert in mass shootings who co-founded The Violence Project. The FBI also declined to talk, even though a judge dismissed the family’s wrongful death claim against the bureau for technical reasons, ruling that the FBI was immune from being sued over its decision not to further investigate Atchison after the 2016 interview.In a brief phone conversation, Atchison’s father, Wayne Atchison, said: “I place a lot of blame on the school system, because he was being bullied and they didn’t do anything about it. They say the FBI’s hourlong exchange with Atchison paints a picture of a young man who exhibited a variety of indicators of violence.“When I read this, it was like oh, my gosh, it’s so concerning,” said Jillian Peterson, a professor of criminology and criminal justice at Hamline University in Minnesota and a co-founder with Densley of The Violence Project.Atchison talked to the agents about having been suicidal. The FBI did alert Aztec police, but the police department never interviewed Atchison, court records show.If the FBI had accessed Atchison’s computer, Robles said, agents would have found ongoing discussions of violence between Atchison and a German man, David Sonboly, who later killed nine people and wounded 36 others in a shooting at a Munich McDonald’s in July 2016. German police uncovered the messages after the Munich shooting, said Florian Hartleb, a German scholar who wrote about the case in a book about so-called lone wolf violence.“There are two dead children in Aztec, New Mexico, [and] nine dead Germans that essentially paid the ultimate price for the FBI not doing what they promised the American public they were going to do,” said Robles, who often represents police officers.Schweit and other experts say the FBI gets thousands of tips every year about people who have said or done things suggesting they might commit violent acts. The FBI agents asked Atchison whether he was willing to speak to a counselor, but there is no evidence in FBI records suggesting the bureau took any steps to facilitate that.“The FBI probably should have been talking to local police, who should have been talking to the school,” Peterson said.