A former student accused of last week’s deadly shooting at a Florida high school returns to court for a hearing in a case that has galvanized advocates of stricter gun control, including many of the rampage survivors.

A teenager accused of fatally shooting 17 people at a Florida high school was investigated by police and state officials as far back as 2016 after slashing his arm in a social media video, and saying he wanted to buy a gun, but authorities determined he was receiving sufficient support, newspapers say.

A troubled teen has confessed to gunning down 17 people at his former high school in Florida, court documents showed, as the FBI admitted it has received a tip-off about the 19-year-old gunman yet failed to stop him.