LOS ANGELES — Sebastian Dumbrava seemed like an ordinary UC Irvine student, studying computer science and applying for summer internships.
Then his life unraveled, beginning with several Reddit posts that led campus police to place him on a psychiatric hold, even though he denied writing them.
He sued the University of California Board of Regents, angry that his prospects of working for the federal government had probably evaporated. He tweeted about suicide and about "serious consequences." He shared a quote about "blood on your hands" from the gunman who killed 32 people at Virginia Tech in 2007.
In January 2020, Dumbrava was arrested after police found a trove of ammunition, large-capacity magazines and the parts to build an AR-15 in his bedroom. Orange County prosecutors believe he intended to shoot up the UC Irvine campus.
Because he had not committed violence or explicitly threatened it, Dumbrava was convicted only of having the ammunition and unlawfully possessing a gun.
He was released from prison after seven months. The judge in the case expressed deep misgivings that Dumbrava was not getting the mental health help he needed and was still a danger to others.
Days after his release, Dumbrava emailed a University of California official and an attorney, demanding $50,000. Now he is behind bars again, facing new charges.
Prosecutors are convinced that he still intends to commit a mass shooting at his alma mater. The new charges — encompassing the emailed monetary demand, which prosecutors characterize as attempted extortion, as well as a revival of previous charges for possessing large capacity magazines — carry a maximum sentence of four years and four months.
Dumbrava's case highlights the challenges of preventing a mass shooting — even after a potential shooter has come to law enforcement's attention.
Dumbrava's attorney, Huy Nguyen, could not be reached for comment. His sister declined to comment when reached by phone.
"We charged this individual not once, but twice, with everything we could possibly charge him with at the state level — and it's not enough," said Orange County District Attorney Todd Spitzer. "He's going to keep getting out, and he's going to keep making preparations to make good on his promises to carry out a Virginia Tech-style shooting at UCI."
Dumbrava's parents divorced when he was 5. With his mother and sister, he left his three-bedroom home in Anaheim for a mobile home in Garden Grove, court records show.
His mother worked as a nursing assistant, sometimes holding down two jobs, according to the records.
After studying at Orange Coast College, Dumbrava transferred to UC Irvine in 2017.
In January 2019, Dumbrava was notified that he was a finalist for a summer job with the National Security Agency's cyber operations program in Hawaii.
He seemed on his way to achieving his dream of working for the agency.
But a month later, campus police discovered some unusual posts on Reddit.
One included the address to Dumbrava's dorm room and suggested that someone "come kill me ... and get 5K."
In late March, a local newspaper employee received an email with the subject line "many will die." Included was an image of a Reddit post with Dumbrava's photo and a note that he "plans to bring [a] gun to campus and shoot random people."
Dumbrava, now 30, denied making the posts and told investigators he was a victim of online harassment.
But campus police suspected that Dumbrava might be planning to hurt himself. They helped place him on a three-day involuntary psychiatric hold.
Dumbrava feared that having the hold on his record would prevent him from obtaining a security clearance necessary to work for the federal government.
"Not only was I judged as guilty without proof, I was effectively imprisoned to a life in which I cannot accomplish my dreams," he later wrote on Twitter.
In August, he sued the Board of Regents, alleging that the psychiatric hold was unlawful and seeking damages for the loss of his career.
In early December, he tweeted a picture of a noose and wrote that he had contemplated hanging himself.
"I have nothing left to live for," he wrote. "Restitution or retribution are the only solutions that will put an end to my suffering."
On Dec. 27, Dumbrava emailed two attorneys representing the Board of Regents, demanding a settlement of $600,000 a year for 30 years.
That same day, he made a $675 purchase on a website that sells parts to build assault rifles, according to a UC Irvine police report.
Because of the psychiatric hold, he was barred from possessing firearms and ammunition.
After the purchase, according to authorities, Dumbrava tweeted a quote attributed to the Virginia Tech gunman: "You forced me into a corner and gave me only one option. The decision was yours. Now you have blood on your hands that will never wash off."
Three days into the new year, Dumbrava drove to Arizona and bought large-capacity magazines and ammunition, according to the police report.
Arizona does not require background checks to buy ammunition, but it is illegal for people to bring the purchases into California.
"Any further injustice committed against me will have serious consequences," he tweeted on Jan. 5.
Less than a week later, police swarmed the Anaheim mobile home Dumbrava shared with his sister and brother-in-law.
Inside a rolling trunk in his bedroom, investigators found more than 1,000 rounds of ammunition and more than 30 large-capacity magazines, as well as the components to assemble an assault rifle.
So-called ghost guns can be built within a few hours from pieces purchased online or produced with a 3-D printer.
Dumbrava was convicted in March 2021 of unlawful possession of a firearm and being a prohibited person in possession of ammunition.
He was sentenced to three years and eight months in state prison, serving about seven months before being released last October.
The judge, Scott Steiner, suggested that Dumbrava needed to be placed in a "mental institution where he can be restored to a place where he's not a danger to people."
"I want the record to at least reflect the deep sense of frustration that the court has at its powerlessness to give Mr. Dumbrava the help he needs," Steiner said. "Because he needs it."
After his release, with an electronic monitor attached to his ankle, Dumbrava slept in his mother's car in Orange County.
Days later, Dumbrava sent an email to an employee at the University of California Office of the President and an attorney representing the Board of Regents in his civil case, requesting they immediately pay him $50,000 for housing and transportation.
He again used Twitter to share his side of the story.
"In the year 2020, I had prepared to commit a mass shooting on the UC Irvine campus. My intent was to cause financial injury to the University," he tweeted on Oct. 25. "I had planned to pursue the shooting of students in the event that the University failed to provide restitution for my injuries."
"I am and will continue to be fully devoted to my pursuit of restitution from The Regents of the University of California," he said in another tweet.
On Christmas Eve, he shared a quote from the Oklahoma City bomber, who killed 168 people in 1995: "A man with nothing left to lose is a very dangerous man ..."
In early January, authorities arrested Dumbrava after he failed to charge the ankle monitor and didn't show up for a mandatory probation visit.
Dumbrava is now facing seven felony charges for the email requesting $50,000, which prosecutors have labeled as an extortion effort, as well as possessing the large-capacity magazines that police discovered in his bedroom in 2020. He has pleaded not guilty and is being held on $1-million bail.
Dumbrava's alleged plot has sparked fear across the UC Irvine campus.
University officials say they have done everything they can to keep students safe, including consulting with federal authorities about Dumbrava.
"We want to assure the UCI community that campus safety has always been our top priority, and at no time was the campus under any imminent threat," said Tom Vasich, a spokesman for the university. "We will continue to take all possible measures to manage this issue."
In one of Dumbrava's last tweets before his latest arrest, he hinted that mass murder was on his mind.
A few years ago, he noted, he had vacillated about his plans, concluding that it would not "feel good to kill students at UC Irvine."
Now, he wrote, "things are very different."
