By The Associated Press

EVANSVILLE — A woman and her young daughter found dead last month in a southwestern Indiana home died from carbon monoxide poisoning after an automobile was left running in their garage, authorities said.

Vanderburgh County Coroner Steve Lockyear said autopsies and toxicology tests revealed that both mother and daughter died from carbon monoxide inhalation. He ruled the death of Kimbra Shanafelt, 49, a suicide and the death of her 5-year-old daughter, Dahni Shanafelt, a homicide.

A relative found Kimbra Shanafelt's body on April 22 inside the garage of her duplex on Evansville's north side. Her daughter's body was found in an upstairs bedroom.

Vanderburgh County Sheriff David Wedding said Kimbra Shanafelt likely died quickly in the house’s attached one-car garage as the vehicle was running. Exhaust fumes then apparently seeped into the house, killing her daughter as the vehicle continued running until its fuel ran out.

Wedding said Friday investigators believe the deaths are likely a case of reckless homicide.

“It’s sad, and it is puzzling. We do wish we could have known what was in the mother’s mind,” Wedding told the Evansville Courier & Press.

“We think her actions precipitated the girl’s death. Did she plan it? We cannot be 100 percent sure," he said. “It’s a head-scratcher because you can’t interview anybody.”

Lockyear said that based on interviews with family members, Shanafelt and her daughter likely died on the evening of April 19.