For days, he had been saying that he had “a secret” that he would eventually reveal, according to screenshots shared by the girl, who asked to be identified only by her nickname, Cece. She said that even when he said he was about to attack the elementary school, she was not sure if he was serious and did not ask a friend to contact the police until after she saw the shooting had taken place, something she regrets.
Cece said on Friday that she had not been interviewed by any authorities since the shooting.
Several other people who met him online said he had sent them disturbing messages.
Kendra Charmaine, a 17-year-old in California, said she had initially met him on Omegle, a website in which people video call with strangers, and that they had begun following each other on Instagram. Soon, he was sending her messages that made her stop responding. “He’d reply to my stories with things like ‘i wanna kill u’ or like ‘i hate you,’” she said.
A study published in 2018 by the F.B.I. found that classmates and teachers were more likely to see warning signs in active shooters who were under 18 (the Uvalde gunman turned 18 eight days before the attack). The study also found that, when people observed concerning behavior in a future gunman, 41 percent reported it to the police while 54 percent did nothing.
The study, which evaluated active shooters between 2000 and 2013, found that people who knew the attackers had observed concerning behavior regarding their mental health in 62 percent of cases. In 57 percent of cases, someone noticed the future attacker having a concerning interaction with another person, and in 56 percent of cases, the person had divulged an intent to hurt people in some way.
Other researchers who have examined mass shootings have found that many of the gunmen targeted their spouses and some had a history of violence against women.
Still, experts caution that many people who fit the profile of a mass shooter never carry out an attack, which can make it difficult for acquaintances to determine whether the person is a real threat or not.
Keanna Baxter, 17, a junior at Uvalde High School, which Mr. Ramos had attended, said he had largely kept to himself but had sometimes been aggressive or intimidating to those around him.
Late last year, she said, Mr. Ramos asked her out. When she turned him down, she said Mr. Ramos began creating different accounts on Instagram to send her harassing messages such as “I hate you” or “I’m going to hurt you.” Still, though, Ms. Baxter said that she had not been afraid of Mr. Ramos, saying she had never expected him to pursue violence, let alone a mass killing.
“Yeah, he was aggressive,” Ms. Baxter said. “But no one ever thought he was sinister enough to do something like this.”
Mike Baker, Shaila Dewan and Jazmine Ulloa contributed reporting.
