The 19-year-old suspect in the Florida high school shooting has confessed to killing 17 people and is “sad” and “remorseful”, his lawyer has said.

Nikolas Cruz, responsible for one of the US’s worst school shootings, cut a pathetic figure in court, where his defence lawyer Melissa McNeil described him as a “broken human being”.

Questions have been raised as to how he was able to commit the atrocity, after classmates painted a picture of an outcast who “everyone predicted” would “do something”.

Cruz himself appears to have presaged the attack. A comment left below a YouTube video by someone using the name Nikolas Cruz warned: “I’m going to be a professional school shooter.”

The comment was flagged to the FBI last September but law enforcement officials were unable to identify the poster and the agency says it still has not conclusively linked the account to Cruz.

Many other disturbing posts were made by someone under the same name. CNN reported that other comments he posted included “I whana [sic] shoot people with my AR-15 [the gun used in the killing spree]”, and “I wanna die Fighting killing shit ton [sic] of people”. An Instagram account associated with the same name included photos of firearms. “Nikolas Cruz” is also said to have insulted Muslims and black people online.

The worrying behaviour was not limited to what appears to be Cruz’s social media footprint. The teenager had disciplinary issues at Marjory Stoneman Douglas high school, which saw him expelled. Florida media reported that teachers were worried about Cruz and that he was not allowed on campus with a backpack, while fellow pupils were wary of him.

Facebook Twitter Pinterest First appearance in court for high school shooting suspect Nikolas Cruz. Photograph: Susan Stocker-Sun Sentinel/AFP/Getty Images

Dakota Mutchler, a 17-year-old junior at the school and a former friend, said Cruz started “progressively getting a little more weird, and I kind of cut off from him”. Mutchler said he posted about killing animals on social media and talked about guns and target practice.



“Everyone in the school that knew him speculated about him,” she said.

Victoria Olvera, also 17, said: “He just changed. As far as I knew, he was like a future school shooter.” Another student told CNN: “A lot of people were saying that it was going to be him. All the kids joked … saying he was the one that screwed up at school, but it turns out everyone predicted it. That’s crazy.”

According to the Sun Sentinel, Cruz’s mother died of pneumonia last November. She and her late husband had adopted Nikolas and his biological brother, Zachary, after the couple moved from Long Island in New York to Broward county.



Play Video 2:26 17 confirmed dead in 'horrific' attack on Florida high school – video report

The boys were left in the care of a family friend after their mother died, a relative said, and moved in with another friend’s family around Thanksgiving. That family’s lawyer, Jim Lewis, said they knew Cruz owned an AR-15. They made him keep it locked up in a cabinet, to which he had a key.

In many ways he seems to have fitted the stereotype of people often associated with carrying out such mass shootings – a loner with a troubled background.

The chief assistant public defender, Gordon Weekes, said Cruz has a “significant” history of mental illness and possibly has autistm or a learning disability, which will renew debate about the ability of people with mental health problems to purchase firearms.

But in the short term the biggest question may surround the FBI’s response to the tipoff about Cruz’s YouTube post.

Agents interviewed the man who reported the comment and searched public records databases, actions in line with the lowest level FBI assessment, but came up short.

The retired FBI assistant director Ron Hosko told the Associated Press: “They owe us some more detail on what they did.” However, he cautioned: “They could spend their entire workforce tracking down internet exchanges that are never going to go anywhere.”

Agents receive tens of thousands of tips each year and more than 10,000 assessments are opened on potentially viable threats.

The statistics provide some explanation as to how Cruz may have slipped through the net but will provide little comfort to those in mourning.