The LAPD did not name Martin but told the Los Angeles Daily News that the suspect had been located and that he is no longer a threat.
"We apologize for the short notice; the safety of our students is our highest priority, " the notification said. "He's not a threat anymore".
"Hashtags of "#MiamiDolphins" and "#HarvardWestlake" were included on the image of the shotgun.
Martin's disturbing Instagram post comes a week after 17 people were killed in a mass shooting at Stoneman Douglas High School in Parkland, Fla., just 33 miles from the home of the Miami Dolphins. "We are working closely with law enforcement and will share more information when we are able".
No charges have been filed against Martin as a result of this incidents, but Harvard Westlake, his high school - also referenced in the Instagram post - was shut down on Friday following the news of Martin's post being reported.More news: Larry Nance Jr. to wear father's No. 22 for Cavaliers
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Harvard-Westlake School in Studio City, California, along with Mr.
Martin, who underwent counseling for emotional issues after the bullying scandal, posted on Facebook in 2015 that difficulties in football led him to attempt suicide multiple times.
In March 2014 though, after vowing he wouldn't return to the Dolphins, the 49ers sent a seventh-round pick to Miami for Martin, reuniting the big tackle with his college coach, Jim Harbaugh.
In what may or may not be a coincidence, the gun picture by Martin was released almost four years to the day that the NFL's investigation on the Dolphins' bullying case was released. Martin was viewed by many as not a victim as much as someone who was o.k. with what was happening, up until he made a decision to walk out on the team from. Several coaches, students and faculty members relayed their support for Martin during this time, including former Head of Upper School and Head of Athletics Audrius Barzdukas, who addressed the controversy in the same Chronicle article from 2013.
In 2013, Martin originally made headlines after publicly accusing teammate Richie Incognito of bullying him both on and off the field. His one season with the 49ers, 2014, was his last in the NFL. But it's not normal to post what Martin would post.