A 23-year-old Rohnert Park woman turned herself in to Sonoma County authorities Friday for what she said was her involvement in the 2012 death of her 3-month old daughter in Billings, Mont.

Amanda Rose Steffan Gilbert went to the Sonoma County Sheriff's Department at 10:50 a.m. and informed investigators of her role in the baby's death, officials said.

Sheriff's investigators contacted the Billings Police Department and a holding order was later issued by Yellowstone County, Mont., for Gilbert on suspicion of murder. She was booked into Sonoma County jail on a no-bail warrant.

Billings police were called to Gilbert's home in June 2012 for a report of a death, according to Billings police Lt. Kevin Iffland.

They arrived to find an ambulance taking the child to the hospital, where she was pronounced dead.

An autopsy revealed the child had injuries consistent with "some sort of foul play," but the cause of death was inconclusive, Iffland said.

"There were injuries that were evident on the baby," Iffland said.

Detectives worked hard on the case and presented their findings to the Yellowstone County Attorney, he said. They felt the facts of the case supported criminal charges for assault on a minor, with the mother and father were both suspects in the case at that time, Iffland said.

The father of the child was listed as 28-year-old Jeffrey Fox, Iffland said.

Investigating officers said the child's room in the home was tidy but the rest of the home was in "disarray," Iffland said.

The department has heard nothing back from the county attorney's office since filing its report, he said.

The detective who worked the case was "very excited" Friday to hear of the break in the case given how frustrating it has been to not bring resolution to such a tragedy, Iffland said.

Sonoma County authorities listed her name as Amanda Rose Steffan Gilbert, which The Billings Gazette reported was one of her aliases. Montana jail officials listed her name as Amanda Rose Steffen-Gilbert.

You can reach Staff Writer Kevin McCallum at 521-5207 or kevin.mccallum@pressdemocrat.com. On Twitter @citybeater.