Mike Taylor, district attorney for the 12th Judicial District

Authorities have not filed charges in the June death of a 3-month-old Marion County infant, but an investigation is ongoing, prosecutors say.

Mike Taylor, district attorney in the 12th Judicial District, said Friday that investigators still are waiting for autopsy reports on Colin Eugene Russell and want to meet with medical officials from Vanderbilt University Medical Center before they decide whether charges are warranted.

"It's still under investigation, and the primary thing is to wait on the autopsy," he said. "Investigators will then sit down with Vanderbilt officials to see exactly what we have."

The district attorney's office then will decide "whether we have a prosecutable case," he said.

The father of the baby, Chris Russell, 23, remains a "person of interest" in the case, Taylor said.

Attempts Friday to contact Russell or the baby's mother, Leah Collins, 24, were not successful. The mother has not been named as a person of interest, officials said.

No other children live with the couple in Sequatchie, Tenn., and neither parent has any prior criminal history or child safety issues, authorities said.

The couple have no other children together, although Russell is father of a toddler from another relationship, officials said. There have been "no issues" related to that child, authorities said.

Taylor said both parents initially agreed to a polygraph test but since have refused to take one. Officials said test results would be inadmissible in court but might provide helpful information.

The probe began in June after an emergency call from family members when the infant stopped breathing the afternoon of June 17, according to investigators.

The child first was taken to Grandview Medical Center in Jasper, stabilized, then transported to Vanderbilt Medical Center in Nashville. There doctors found what they characterized as "major trauma" to the baby's brain, Sheriff Ronnie "Bo" Burnett said.

The baby died after the family decided to discontinue life support June 23, Burnett said.

Marion County Detective Beth Schindel, the primary investigator on the case, said early on that medical scans and an MRI exam performed before the baby died showed he had retinal hemorrhaging and brain trauma, injuries similar to those found in cases of shaken baby syndrome.

They also found fractured ribs that "were at least 10 days old," and the baby had been throwing up - a possible sign of brain injury - for a few days before he stopped breathing, the detective said.