ANCHORAGE, Alaska — A woman has been indicted on murder charges in the deaths of her two baby daughters two years apart.

A Fairbanks grand jury Wednesday indicted Stephany Lafountain, 23, in the death of a 4-month-old girl in 2015 and a 13-month-old girl in November 2017.

Both girls’ deaths exhibited signs of being suffocated, police said. The girls were referred to by their initials and their names were not released.

At a news conference, Fairbanks Police Chief Eric Jewkes called the cases an “unimaginable tragedy,” but did not discuss a possible motive.

Fairbanks police arrested Lafountain on Thursday afternoon. She was jailed at Fairbanks Correctional Center. Online court records do not list Lafountain’s attorney. She was scheduled to be arraigned Friday.

Lafountain last year was married to a soldier and living on Fort Wainwright Army Post. The Fairbanks Police Department investigated the Nov. 20 death because the mother and the child were civilians, authorities said.

Online court records indicate she was divorced in February.

According to police, Lafountain called emergency responders just before 6:30 p.m. to say her child was not breathing. The child was taken to Fairbanks Memorial Hospital and later transferred to Providence Medical Center in Anchorage, where she died four days later.

As part of their investigation, police reopened an inquiry into the death of Lafountain’s infant in 2015 when she was in a previous relationship. At the time, police said, the death was not considered a homicide.

Police said they then found similarities in the two cases.

Lafountain, then named Stephany Bilecki, and living in a Fairbanks apartment, called police just after 5 p.m. on Sept. 15, 2015, and said her 4-month-old child was not breathing.

The child was later pronounced dead at Fairbanks Memorial Hospital.

Detectives learned that an hour before her second child died, Lafountain searched online on how to kill without being detected. Among the searches: “Ways to suffocate,” ″Best ways to suffocate” and “Ways to kill human with no proof.”

Lafountain also searched whether drowning could show up in an autopsy report, “suffocating and smothering” and how to commit the perfect murder, police said.

Autopsies and medical records indicated both girls were healthy and suffered no genetic abnormalities, diseases or injuries. The first girl’s death was officially undetermined but showed characteristics of suffocation. The second girl died of complications of anoxia, or lack of oxygen to the brain.

Lafountain is charged with counts each of first- and second-degree murder in both deaths.