By the time Nicholas Cruz was a teenager, he had been sneaking into his neighbors' yards yard across the street and trying to get his dogs to kill their baby pigs. In recent years, the behavior had gotten worse. Cruz had become more isolated, withdrawing from his classmates, friends and brother. But no one would have ever suspected the violence in Cruz's heart until Valentine's Day, when police say he carried out one of the nation's deadliest school shootings.

Cruz was adopted at age two along with his two-month-old brother, Zachary, by Linda and Roger Cruz. Their adoptive father died of a heart attack when they were young, leaving Linda to care for both of the boys on her own. Zachary seemed quiet and followed Nikolas' lead. However, Nikolas was moody and prone to an explosive temper. Cruz picked fights with other kids and many people were afraid of him. He seemed to take delight in antagonizing others.

Cruz began selling knives out of a lunchbox and posting pictures on his Instagram about guns and killing animals. Cruz was suspended from school repeatedly until he was expelled last school year. Cruz's mom died of pneumonia at 68. With her death, he lost one of the people closest to him. A family gave him and his brother a place to live. They got him a job at a local dollar store and saw signs of depression, but nothing of anger.

Then, on Wednesday, Cruz said he wasn't going to school. That morning, the family's son, however, went as usual to school. When the shooting began, he was in class and remained locked in the room until the police let him out. That, Lewis said, was the first indication of the violence that was inside Nikolas Cruz.