Cobb County man sentenced to life for arson attack that killed girlfriend's mother, grandmother

COBB COUNTY, Ga. - A Mableton man will spend the rest of his life in prison for murdering his then-girlfriend's mother and grandmother in an arson attack.

On Wednesday, a Cobb County jury found 32-year-old Robert Colt Smith guilty of felony murder, first-degree arson, aggravated battery, and aggravated assault.

What we know:

According to prosecutors, Smith had violently attacked his 19-year-old then-girlfriend on Valentine's Day in 2022, leaving her with black eyes and a shoe print on her face. He was arrested for that attack and released on bond.

A year later, officials say Smith hospitalized the woman twice in just two weeks and was arrested again. This time he was released on bond under a no-contact order, but officials say he convinced his victim to continue their relationship.

When the woman's mother, identified as 52-year-old Andrea Nall, tried to have Smith's bond revoked, officials say he retaliated on the morning of March 12, 2023.

That day, Smith reportedly set fire to a vehicle parked outside the woman's home on Janet Lane in Austell used spray paint as an accelerant. The fire then spread onto the nearby carport and the home.

Nall and her mother, 74-year-old Michelle Lacroix, and eight pets were inside the home at the time of the fire. All of them died from smoke inhalation.

Michele LaCroix and Andrea Nall (FOX 5 Atlanta obtained permission from the family of the victims) ( )

Investigators quickly identified Smith as the suspect and arrested him for the crime.

What they're saying:

"This community was robbed of two amazing women who opened their home as a refuge," said Senior Assistant District Attorney Jared Horowitz. "These two mothers did what any parent would—protect their children from an abuser. But this defendant used fire to seek revenge. Justice prevailed today, and his reign of terror is finally over."

What's next:

Following the guilty verdict, Superior Court Judge Kellie Hill sentenced Smith to two life sentences plus 20 years in prison.