Parkland, Florida (CNN) Joelle Guarino says she knew Nikolas Cruz was going to shoot up a school. She just didn't know when.

"I had no doubt he was going to do this," Guarino told CNN. "My husband and I both knew that we would eventually see him one day on the news, wearing an orange jumpsuit being charged with murder."

When the news broke that a gunman had terrorized Marjory Stoneman Douglas High School in Parkland, Florida , Guarino said she knew it was Cruz, her former neighbor, a boy she saw grow up alongside her own children.

Guarino said her home was the house in the suburban neighborhood where all the kids on the street hung out, including Cruz. They played on her large grassy lawn and swam in the backyard pool.

Cruz, she said, never looked her in the eyes. Another neighbor described Cruz the same way: He liked wearing a hoodie and walked looking down, never speaking much.

"He was dealing with something dark," a neighbor who would only speak anonymously said. "I just didn't know what."

Guarino said the signs worried her early on. She remembers Cruz was a baby when he hit one of her sons repeatedly with a plastic toy. His mother, Lynda Cruz, she said, started hitting him and asking him not to hit others.

A few years later, Cruz locked himself in one of Guarino's rooms, she said, and destroyed a toy train set after he spilled soda and the kids told him it looked like he had urinated on himself.

Later, when Cruz and her children were all 10, she said Cruz threw a rock at her son and hit him in the eye.

Guarino said she started to notice odd things inside the Cruz home, too, before ending her friendship with Cruz's mother. Lynda Cruz kept the pantry and the refrigerator under lock and key, Guarino said. She remembers feeding Cruz in her home because he was hungry. And Cruz's room was filled with holes, she said, created out of anger when Cruz got mad and punched the walls.

Paul Gold, another longtime neighbor, also said Cruz's room was filled with holes. And he said Lynda Cruz kept the food locked up not because she was abusive, but because she was on a tight budget and sometimes ran out of food for the boys.

As Cruz got older, Guarino said, she started noticing Cruz killing toads on her lawn, by piercing the animals with spear-like objects; then he would dissect the animals. But it was when Cruz was in eighth grade that she said she saw an even darker side.

Guarino said Cruz was standing over her dog Max with a menacing expression while Max was convulsing and foaming at the mouth.

"His face was excited that it was happening -- with this wild satisfaction look," Guarino said. "As soon as he saw me his demeanor changed."

After that, Guarino asked her sons to keep their distance from Cruz, and to avoid making him angry. She was afraid of what Cruz was capable of doing.

From across the street, Guarino saw other worrying signs, such as Lynda Cruz calling law enforcement on her sons for domestic "disturbances" and then -- as law enforcement reports show -- telling police no violence was involved.

The descriptions of the police calls include things like "hitting door with pool equipment," "throwing items" and "physical altercation." Guarino said she remembers seeing deputies detaining Cruz in the back of a squad car, and then releasing him.

"Lynda always denied it. She would blame it on everyone else," Guarino said. "She would excuse him for everything."

Guarino noticed other odd things, like the text messages Cruz sent her son saying he "got 12 kills today" after playing paint ball, she said, and Cruz using his BB gun to shoot at squirrels, birds and other small animals.

Guarino said she wrestled for years with the question of what to do about Cruz, and she worried from a distance about the safety of her own children.

She said one day her son walked into her kitchen and showed her a Cruz Instagram post featuring a photo of an AR-15-style rifle, with a caption about how he couldn't wait to buy one when he turned 18. Soon after, there was another post, one in which Cruz said he wanted to "shoot up a school." Guarino said all these warning signs flashed before her eyes.

She said she called 911 and begged the responding officer to do something.

"There is nothing I can do," she said the deputy told her. "Until he does something there is nothing I can do."

The Broward County Sheriff's Office has not replied to CNN's request for comment on the call.

Guarino said she felt defeated. Scared. Afraid for her children. She told the deputy she wanted to stay anonymous, and she thought about moving away from the neighborhood. Later, she felt relieved when the Cruzes moved out in 2017. Lynda Cruz died later that year.

But Guarino's worst fear became a reality when 17 people were gunned down at Marjory Stoneman on Valentine's Day.

"I knew in my heart that he was going to do it," Guarino said.