CHATTANOOGA (WRCB) -- Jeremy and Mary Fry entrusted their sister-in-law, Jessica Fax, to care for their 12-week-old daughter and her three older sisters while they worked nights at Silverdale and Hamilton County's 911 Center.

But October 9th, their baby, Mia Fry, died. The next day, Hamilton County sheriff's detectives charged Fax with criminal homicide.

Tuesday, Mia's parents testimony at Fax's preliminary hearing, helped a Sessions Court Judge decide to send Fax's charges to a grand jury.

Jeremy Fry testified that baby Mia seemed herself when the family had dinner before he went to work October 8. Fax made no mention of any problems overnight, when he returned home a little after 7 o'clock the next morning.

"I looked in on her (Mia) and she looked like she was sleeping, so I didn't want to wake her up," Fry told the court.

But three hours later, he still hadn't heard any cries, or sign that Mia had awakened.

"By now, she'd be squirming around and fussing a little," Fry testified. "I went to go check on her and well, she didn't move like she normally would, and I noticed she was cold."

His voice struggling not to break, Fry would describe taking Mia to the couch in the living room, asking his wife to call 911.

"What did Miss Fax say when you said this," Public Defender Alan Dunn asked.

"She said, Oh No," Fry replied.

He would tell Fax to take the other children to the basement so they wouldn't learn there was trouble.

Baby Mia was long dead, Hamilton County Det. Rick Whaley told the court.

"She was in full rigor mortis, " Det. Whaley said. "If the ambulance time is correct that would put her time of death at approximately six to eight hours earlier."

Mia had had breathing problems, her father testified. "She had soft cartilage in her throat, floppy, she would aspirate."

It's why he and his wife moved her crib into their bedroom. Fax would sleep their when she babysat her own daughter and the Fry girls.

"We assumed it was SIDS (Sudden Infant Death Syndrome)," Mary Fry testified.

The next day, the autopsy report would deliver a verdict more definitive. And gruesome.

"There was some serious skull fractures," Det. Whaley testified. "Spider web cracks, overlapping eggshell cracks. And one on the left side that ran to the top of the infant's head."

At first, Fax denied knowing anything about what happened, Det. Whaley said.

"But when we told her it was blunt force trauma, she told us that she had the child in her lap and dropped the child on the floor."

Fax's account was inconsistent with Baby Mia's injuries, Det. Whaley later explained.

"The floor was carpeted. The carpeting had padding."

The time frame that detectives established is critical to their decision to charge Jessica Fax with criminal homicide.

It leaves her as the only adult in the house when it happened.

"Never had trouble with the other children around the baby," Public Defender Dunn asked Mia's father.

"No, they were really careful around her," Fry responded.

"Did you verify that (Jeremy & Mary Fry) were at work," Dunn asked of Det. Whaley.

"I haven't gone back and picked up the work records, if that's what you mean," Whaley answered.

Judge Johnny Houston ruled that the collective weight of the evidence is sufficient to send the case to a grand jury.

"Do you have any questions," Judge Houston asked of Jessica Fax.

Her softly murmured "no" was her only audible remark during the entire hearing.

Cuffed and shackled, Fax slouched as she sat at the defense table; staring at her feet, making no eye contact.

Her bond remains $125,000. She remains housed in Bradley County, rather than Hamilton County's jail for female inmates; Silverdale.

Mia Fry's mother works at Silverdale.