LANSING, Mich. (WLNS) — 6 News has an exclusive new video and we’re learning more about the woman Lansing police said is responsible for killing a grandmother and her two grandkids.

21-year-old year Abbieana Williams is in custody and charged with three counts of murder and arson. Police said she set a house on fire on Elizabeth Street earlier in September. Three victims were trapped inside while the home burned.

We want to warn you that the video attached to this story and some details shared by Mike Collier, who is the son and uncle of the victims is graphic and disturbing.

“She’s always done that,” Collier said about Williams. “She’s always threatened my family all the time about doing that.”

Collier said he never thought Abbieana Williams would act on her threat and be this violent.

“Not even a little bit,” he said.

That was until Sep. 3, the night of the fire. Now, he says his family is devastated.

“She was a whole different character as a grandmother,” Collier said. “I loved it. Why, why did you do that. What made you go take three innocent lives.”

Along with telling us about threats made by Williams, Collier showed us a video. He said it shows Williams getting violent with his brother while holding a knife and that it happened earlier this year. He said this happened after Williams assumed his brother was cheating on her.

Collier said this wasn’t the first time something like this has happened. He said, “She’s busted out windows that I had to repair for them just because it’s my brother.”

Collier said he knew Williams was responsible for the house fire. The night the fire happened, he said he saw the messages Williams sent to his brother about burning his mother alive.

Collier says the threats made this time were because Williams again thought his brother was cheating.

“I feel better knowing that there’s actually justice being served for that because, in the beginning, it was just going to be considered an accidental fire and I’m glad everything worked the way it did for my mom and my nephews,” He said.

The mother of the boys said they were loving, smart and funny.

Collier tell us there are several other videos like this.

We did reach out to the mother of Williams to talk about her daughter, but she did not get back to us before this story aired.