(NewsNation) — A former classmate of the person who allegedly shot and killed six people at a Nashville school is shocked by the tragedy, describing the assailant as someone who was “kind” and “sweet” but could also be “jittery” as a teenager.

Samira Hardcastle went to middle and high school with Audrey Hale, the 28-year-old who police killed Monday inside The Covenant School. Police said the shooter was a former student and had detailed maps of the school, as well as a manifesto.

The community is still searching for answers, particularly a motive behind the attack.

“Growing up, she was very sweet, very kind, just loving, and everyone to my knowledge was kind back to her. They reciprocated that energy because she was so loving,” Hardcastle said Wednesday on “CUOMO.” “My personal experience was that she was kind. However … her personality or her body language was a little bit jittery or energetic, so maybe jumpy, but I also think that she was on the autism spectrum, so that could have played a part, as well.”

Police have not confirmed much about the shooter, but they said Hale did identify as transgender. Officials said they are still investigating if Hale’s gender identity played any role in the shooting.

Dr. John Delatorre, a forensic psychologist, believes gender identity was likely not that relevant.

“I think it could be sort of a distraction from when it comes to the sort of ultimate psychopathology that might be going on,” Delatorre said Wednesday on “CUOMO.”

He explained that while mental illness doesn’t cause violence, it can make someone more susceptible to underlying influences such as grief or trauma.

“These kinds of individuals, when they’re in a depressed state, when they’re in (an) anxious state, can all of a sudden start generating delusional thinking … mistaken beliefs about the world … whatever makes you you is seen as a problem for some individuals,” Delatorre said. “In that state, you can start thinking about what it was to be like to to live in a world in which you can get that control back, and often times, getting that control back can be used as a method for violence.”

Hardcastle and Hale attended the Nashville School of the Arts, which Hardcastle said is known for being welcoming of the LGBTQ community.

“There was nothing that hinted that she could be capable of something so evil and heinous,” Hardcastle said.

Police have said they plan to release the manifesto, which may help shed new light on the shooting.

“We’re just in complete shock and nobody knows exactly how to wrap their minds around it. Of course, we’re not justifying what she did, there’s no excuse for it,” Hardcastle said. “But we do have memories of her being sweet and you know, that’s a reality even if other people don’t want to hear that. She was sweet, that’s just what it was.”