As they dated this spring, they bonded over their struggles with mental illness, she said, so his dark thoughts didn't seem so abnormal. Not to her, as someone familiar with the alarm bells therapists listen for. Not at the time.
Now? Now investigators are trying to figure out why Betts, 24, gunned down nine people, including his own sister, and wounded many more Sunday outside a strip of bars in Dayton, Ohio, before police shot him dead.
And Johnson is playing those old episodes back over in her mind, the yellow flags turning red, wondering whether she should have broken his confidence to tell someone — and if she had, whether it would have mattered. At a minimum, she regrets not telling his parents he needed serious help.
"It seems easy on the outside looking in, what calls to make," Johnson said Tuesday. "And looking back, I'm like, 'Of course I should have done that.' But in the moment it was complicated, it was weird and I cared about him. I didn't want to hurt him."
Besides, she said, reaching for a phrase favored by mental health professionals: "He didn't have any concrete plans." Johnson's lengthy essay posted not long after the massacre and her interviews with The Associated Press and others offer a rare, raw glimpse into the dilemma facing those close to people who voice such demons.
When is it just someone trying to exorcise those thoughts by saying them out loud? When does it foreshadow the worst? And does intervention run the risk of pushing the person even further toward violence?
Complicating that calculus: Mass attacks involving mental illness aren't about that condition alone, or about an event that sets someone off. Experts say there are multiple factors — access to guns, a history of violence, substance abuse, financial trouble, a disconnect from society.
"There are many, many, things that go into dictating what pulled the trigger," said Jonathan Metzl, a psychiatrist and professor at Vanderbilt University. "There's no tool you can have to determine when someone is going off."
Studies from the FBI and Secret Service looking at those who carry out mass attacks show almost half were agitated by personal grievances and most had never been diagnosed with a mental illness. Johnson met Betts last January at Sinclair Community College in Dayton. He stood out because he was charming, funny, intelligent and quick-witted, she said.
He also told her he had bipolar disorder and might also suffer from obsessive-compulsive disorder, she said. Betts had a fascination with serial killers and tragedies in the news. "He was interested in what made terrible people do terrible things," she said.
On their first date in March, he showed her a video of last year's Pittsburgh synagogue shooting, going over it play-by-play. Talking about serial killers made sense because it often came up in their psychology class
"Half of our class was into serial killers," she said, adding that she figured his admissions of twice putting a gun in his mouth before they met was normal for someone grappling with mental illness. "That wasn't a scary thing for me," she said.
Johnson said she worried about his excessive drinking and didn't like that he had guns. She also said, however, that she and Betts didn't think people with mental illnesses shouldn't be allowed to own guns.
But she said many people in the Midwest own firearms, and that the one time they went to a shooting range, he handled the guns carefully and seemed more like a hobbyist. When she thought about alerting someone after he talked about wanting to hurt people, "it came back to, 'But what would I tell them, what would they do with it?'" she said.
She also considered talking to his mom, but wondered how he'd react to that. "You can't just tell someone and expect there not be any consequences for anyone," she said. "It's a tough situation." Johnson showed The Associated Press text message exchanges with Betts and an email showing they were in the same class last winter to corroborate their relationship.
Betts lived with his parents while they were dating, she said. His room decorated in all black was a striking contrast to the flowery, bright patterns throughout the rest of the home. He was in a heavy metal band whose members dressed in matching costumes: ski masks and dresses.
It all seemed harmless, she said. "What most people saw as red flags, I saw as yellow flags, up until the stalking," she said. That's what pushed her to break up with Betts in May. One afternoon, he said he wanted to give a letter to a friend who had moved into town. She thought it was sweet.
But when she saw the letter, she realized it was for an ex-girlfriend and it carried an ominous message: "You can't outrun your past." That time, Johnson said, he tried to downplay it as a joke, but she knew it wasn't. When she pushed him to explain, she said he spoke of "uncontrollable urges to do things," including a time he set fire to an abandoned building. She said she knew she had to end it.
Dayton Police Chief Richard Biehl said earlier this week that Betts had a "history of obsession with violent ideations with mass shootings and expressed a desire to commit a mass shooting." Todd Wickerham of the FBI said "we have uncovered evidence throughout the course of our investigation that the shooter looked into violent ideologies," though the agent didn't specify.
Several of Betts' high school classmates have said he was suspended for compiling lists of students he wanted to rape or kill. Johnson said she didn't know about that. She doubts anyone will ever fully know Betts' motive for the shooting.
"It's more than mental illness, it's more than gun control," she said. "This isn't just one simple issue and for people to blame it on one thing isn't fair. "I'm not shocked he did something terrible, because he had untreated problems," she said, adding that "there are millions of people with mental illness who don't go around shooting people."
Associated Press writers Matt Sedensky in New York and Michael Biesecker in Washington contributed.