Heidi Broussard’s Mother Believes Her Daughter’s Best Friend ‘Premeditated’ Her Murder

The mother of slain Texas mom Heidi Broussard is speaking out after her daughter’s friend Magen Fieramusca was indicted on murder and kidnapping charges.

In a new interview with NBC’s Dateline, which will air in full on Friday night, Tammy Broussard spoke about her grief over Heidi’s death, and also said she believes Fieramusca “premeditated” her daughter’s murder.

You’ll get the latest updates on this topic in your browser notifications.

“She premeditated all of this,” Tammy said in the interview. “We really want to know why. Why would you hurt a friend? I mean, you’re supposed to be her friend. Why would you do that? We would just like to know why.”

Tammy also claimed that Fieramusca’s “only concern” after Heidi went missing was “wanting to know are the police doing anything.”

“All I can say is she had planned this for a long time,” Tammy alleged. “I believe she planned it whenever Heidi said she was pregnant.”

Heidi Broussard
Austin Police Department

During the interview, Tammy also grew emotional while speaking about her late daughter, who was first reported missing on Dec. 12.

“You know, it’s like you see a table full of candles and all lit, but then they go and snuff it out like that,” she said. “That’s what she did. She took the light away. Heidi was a light in everybody’s life.”

Heidi was mother to newborn baby Margo Carey, as well as a 6-year-old son named Silas.

“I will keep talking about her and keep her alive in their hearts,” Tammy said on Dateline. “She was the biggest blessing in our life.”

RELATED: ‘I Don’t Understand What Happened:’ Fiancé of Texas Mom Heidi Broussard Speaks Out

On Tuesday, Fieramusca was indicted on charges of capital murder and kidnapping in the death of her friend Heidi. The one-page indictment obtained by PEOPLE alleges that Fieramusca, 34, asphyxiated Heidi, 33, by “ligature strangulation” — with “a leash” and with “her hands.”

Magen Fieramusca
Courtesy of Humble Police

RELATED: Woman Who Kidnapped Best Friend’s Baby Strangled the New Mom with a Leash, Police Say

Heidi and then-2-week-old baby Margo went missing in December. After an intense search, the infant was found alive a week later in the Houston-area home where Fieramusca was living, authorities said. Broussard’s body was discovered inside the trunk of a vehicle in the driveway of the home.

In early January, the baby was reunited with her father and brother after being held for a DNA test in order to positively identify her.

Want to keep up with the latest crime coverage? Sign up for PEOPLE’s free True Crime newsletter for breaking crime news, ongoing trial coverage and details of intriguing unsolved cases.

Fieramusca’s attorney, Brian Erskine, did not immediately respond to PEOPLE’s request for comment on Tuesday, but told CNN in a statement: “Exculpatory and mitigating evidence has a shelf-life, and too many individuals in our criminal justice system have been delayed or denied this information.”

“We cannot act to fairly and vigorously represent our Client when we start defending her with our hands tied and eyes blindfolded,” he said. “Justice ought to be blind, not the defense.”

More of Tammy’s interview with Dateline will air at 10 p.m. on Friday night on NBC.