WTSP A Miami father, concerned over some of his son’s disturbing social media posts with guns, leads to the teenager’s arrest. That’s because when the father turned over his son’s smartphones to police, they also found child porn, police say. Sean Mesa, 18, a senior at Dr. Michael Krop High School, is now charged with possessing child pornography, as well as improper display of a firearm, the Miami Herald reports. Mesa’s father told police he was worried about his son’s posts with guns on his Instagram and Snapchat in the wake of the Marjory Stoneman Douglas High School massacre. Ever since the Valentine’s Day school shooting in Parkland, police have tightened responses to online threats. Before the shooting, self-confessed shooter Nikolas Cruz had come to the attention of local and federal authorities for his disturbing online posts with threats and weapons — red flags that were never investigated. Sean Mesa came to the attention of U.S. Homeland Security Investigations’ Violent Gang Task Force, which forwarded his Instagram and Snapchat photos “recklessly displaying firearms and pointing them at the camera,” according to an arrest warrant. Miami-Dade Schools Detective John Messenger went to Krop High School on Tuesday to “engage in a friendly conversation to understand what Sean Mesa’s fascination with firearms was.” Mesa reportedly bristled, telling Messenger “he liked guns and it was his right to post on social media whatever he wished,” according to The Herald. But Mesa’s father agreed to give police Mesa’s two phones, which the Secret Service examined and found a video of what appeared to be a child under the age of 10 being sexually abused, according to the warrant. The video had also been sent to two others in a group chat, the warrant said. Using other devices, Mesa continued posting on Snapchat. Another post showed a pistol on his lap with the caption: “now they watching so I ain’t stopping.” “The latest Snapchat photos have students and staff at Dr. Michael Krop Senior High alarmed and afraid,” according to the warrant.