Cayden's mother says she tried to shield him from dangerous things like subway surfing but he knew about it from friends and social media.
"It's unbearable. How am I supposed to find peace? My boy is gone," Jaida Rivera said.
Rivera's son died while subway surfing nearly two weeks ago.
The heartbroken mother wants answers as to how her 11-year-old left school that morning and found himself on top of a moving train.
"Where's the security? Where's the locked door? Where's the staff? It doesn't make sense," she said.
Rivera says her mother dropped Cayden off at Fort Greene Preparatory Academy at 7:45 that morning.
Staff saw him eating breakfast in the cafeteria, but he was marked absent when attendance was taken just 30 minutes later.
According to police, Cayden was riding on top of a G train when he fell onto the tracks at the Fourth Avenue-Ninth Street station just after 10:00 a.m.
Rivera says the school didn't notify her or any other family member.
"He was left in their care, where is the responsibility? Growing up teachers used to be second parents to us. I trusted him with my kids, but they didn't keep him safe," Rivera said.
Cayden is the fourth and youngest child to die subway surfing so far this year.
The MTA says it's working with social media companies to flag and remove posts the show this dangerous trend.
Interim NYC Transit President Demetrius Crichlow released a statement on Friday:
"This tragedy is another heartbreaking reminder that riding outside trains is not a game. It should not take more loss of young lives for those who would climb on top of subway cars to comprehend the devastating risk."
The transit agency has also released PSAs, but Rivera's attorney says this is far from enough.
"It's terrible that the New York City transit authority is not doing a better job of policing subway surfing. Is not doing a better job radioing each other to slow trains down when they see surfers on top. It's really a tragedy that this is continuously happening in our city," attorney Rikki Davidoff said.
The attorneys are taking steps to file a lawsuit against the MTA and the Board of Education.
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