Jonathan Martin played in the NFL from 2012 through 2014 and was at the center of a bullying scandal while a member of the Miami Dolphins

By Greg Hanlon and Chris Harris
February 23, 2018 03:44 PM

A prestigious Los Angeles prep school was forced to close today after a threat was posted on the apparent Instagram account of a former NFL player who is an alum of the school, PEOPLE confirms.

Jonathan Martin attended the Harvard-Westlake School, in Studio City, before playing in the NFL from 2012 through 2014. He is best known for being the alleged victim at the center of a bullying scandal with the Miami Dolphins that made headlines in 2013, when Martin left the team and accused several teammates of bullying him.

The Instagram post apparently from his account that compelled the school’s closure shows a shotgun with shell casings around it, along with threatening text.

It references both Harvard-Westlake and the Dolphins.

A Los Angeles Police Department spokesman tells PEOPLE, “An individual we believe is responsible for the social media post in question has been detained and our investigation is ongoing”

The Instagram post also includes the Twitter handles of Richie Incognito and Mike Pouncey, two of Martin’s Dolphins teammates he had accused of bullying him.

Girls play a game of field hockey on the athletic fields of Harvard-Westlake School, an independen
Harvard-Westlake School
| Credit: Luis Sinco/Los Angeles Times/Getty

• Want to keep up with the latest crime coverage? Click here to get breaking crime news, ongoing trial coverage and details of intriguing unsolved cases in the True Crime Newsletter.

In a message sent to students Friday morning, the school said it became aware of a “disturbing social media post that mentioned Harvard-Westlake by name” late Thursday night, the Los Angeles Times reports.

“The safety of our students, faculty, and staff is always our primary concern. So, out of an abundance of caution, we made the decision to close school today,” the email read. “The school’s private security team is working with the Los Angeles Police Department, which is present on both campuses. With these precautions in place, we believe there is no imminent threat to our campuses or our school community.”

• For more compelling true crime coverage, follow our Crime magazine on Flipboard.

Martin is a 2008 graduate of Harvard-Westlake. In 2015, according to the Times, Martin posted on Facebook and Twitter about his struggles at the school, saying he was “one of just a handful of minorities in elite private schools.”

Jaguars Dolphins Football, Miami, USA
Jonathan Martin
| Credit: Wilfredo Lee/AP/REX/Shutterstock

“You learn to tone down your size & blackness by becoming shy, introverted, friendly, so you won’t scare the little rich white kids or their parents,” he wrote. “Neither black nor white people accept you because they don’t understand you. It takes away from your self-confidence, your self-worth, your sanity.”

Maggie and Jake Gyllenhaal, Sally Ride and Candice Bergen are Harvard-Westlake alumni.