One of Cruz's family members, who remained unnamed, told the network that Nikolas had been adopted by Roger and Lynda Cruz.
"The gunman's mother, adoptive mother, passed away in November of last year," Kaye told CNN anchor Don Lemon. "November 1, in fact. She had the flu, it turned into pneumonia and she passed away. The father had died 13 or 14 years ago. This cousin was asked 'Who did he live with? Who took care of him?' The cousin said that he's pretty much been on his own. Whether or not that speaks to what happened here today, what some of his motive was, still unclear at this time."
In a separate report, The New York Times reported that Lynda Cruz used to resort to calling the police to have them come to their home and calm down Nikolas.
"I think she wanted to scare them a little bit," Helen Pasciolla, the Cruz family's neighbor, told the paper. "Nikolas has behavioral problems, I think, but I never thought he would be violent."
Cruz was expelled from Marjory Stoneman Douglas High School in Spring 2017 for what has been described as "disciplinary reasons."
Teacher Jim Gard told The Miami Herald that Cruz was not allowed back on the school grounds.
"We were told last year that he wasn't allowed on campus with a backpack on him," Gard said. "There were problems with him last year threatening students, and I guess he was asked to leave campus."
Broward County Public Schools superintendent Robert Runcie said in a press conference that concerns of Cruz acting violently never reached his office.
"We received no warnings," Runcie said. "Potentially there could have been signs out there. But we didn't have any warning or phone calls or threats that were made."
Following his expulsion, Cruz got a job at a Dollar Store.
"I went there and asked him what happened once," Cruz's former classmate Ocean Parodie told The Daily Beast. "He said he was expelled and was happy that he was thrown out. I felt bad for him. I think just to treat someone differently [for] how they look is wrong, so I tried to treat him like I treat everyone else."
Cruz, wielding an AR-15 semi-automatic rifle, opened fire inside the school minutes before class dismissal on Wednesday afternoon. Twelve people, including the school's athletic director, were killed, three more were killed outside the building and another two died after being transported to the hospital. Fifteen victims remain at area hospitals, with five reportedly still in critical condition.