In a letter to parents, the district's chief of police said the police department worked with the FBI to track down the student, who is now expelled.
The Klein ISD police department says it is working with the Harris County district attorney on criminal charges.
This came after the school received a string of social media posts Monday and Tuesday threatening violence against the campus.
"Those are not unique to Klein Cain or any Klein ISD school," Chief David Kimberly said at a press conference Wednesday. "Those are actually a national trend right now, and it's very disturbing."
Full news conference from Klein ISD police
Kimberly asked the public for a favor when it comes to threats posted on social media.
"If you see it, share it. Don't spread it," he said.
Kimberly explained that it is best for social media users to share the posts with local law enforcement and campus administration instead of with friends and family online.
"Please do not take and put it out on your social media. Please don't put it out there looking for the community's input," Kimberly said. "Because sadly, most of the time, they don't have the answers."
He said the hundreds of shares muddy the investigation, causing investigators to waste valuable time on bad leads.
"Somebody says, 'I know about this threat.' So we reach out to them, only to find out it's their cousin's barber's best friend," he explained. "Even if a person just simply shared it, we may knock on your door at 2 a.m. to ask you where you got the information because we believe this is critical."
Kimberly had a message for Klein ISD students when it comes to anonymous threats.
"This is not a prank. This is not a joke. This is not a way to get more likes or shares," he said. "You may get notoriety, but it's not the kind of notoriety you're looking for."
He had a different message for parents.
"To my parents, if you're not involved in your child's cell phone usage in their life, I can't implore you enough to please get involved," Kimberly said.
In a letter to parents, Nicole Patin, the principal of the school, also asked parents to monitor their child's social media accounts.
"A disturbing social media trend has emerged across the nation, which involves students posting disruptive behavior on social media at schools to gain likes," Patin said. "These posts are not always accurate, spread misinformation, and disrupt the learning environment."
Out of an abundance of caution, backpacks will not be permitted on campus for the remainder of the semester. Students are still allowed to bring their laptops and may instead bring small clutch bags.
The district said it would make an announcement when backpacks are allowed again.
"I'm a parent. I have kids," Kimberly said, "I can't begin to express how disappointed we are. We're better than this. As a community in Klein ISD, we are better than this."
Additionally, the principal said Klein ISD police and Harris County Precinct 4 Constables will continue to be highly visible on campus.
Klein ISD police will use canine detection services to conduct random searches of vehicles and campus areas, Patin said.
Eyewitness News is following the developments out of Klein Cain High School. Get the latest updates by following Roxie Bustamante on Facebook, Twitter and Instagram.