Six years ago emergency workers carried a gasping 18-month-old girl covered in bruises into an ambulance, trying to save her life.
Two days later, Sierra Carpenter died.
Police believe that only two people could have caused the bleeding in her brain and in her eyes, the deep bruising in the recesses of her ears - the fatal injuries that led doctors to take her off life support.
One of those people - her mother's boyfriend - was acquitted by a jury. And there is some doubt whether the other -Sierra's mother - ever will face trial.
At least four trial dates for Traci Carpenter have come and gone. She faces more than two decades in prison if convicted of aggravated child neglect, the charge lodged against her.
But if Tennessee's highest court agrees with Carpenter's lawyer, prosecutors may lack enough evidence to win a conviction and could be forced to drop the case.
Last week the Tennessee Court of Criminal Appeals denied her attorney's request that it review the charges against her before she stands trial.
Now attorney Lee Davis says he will ask the Tennessee Supreme Court for a rare pretrial ruling on what he sees as changes in admissible evidence in child neglect cases.
Davis argues that a state Supreme Court decision in a similar case earlier this year now prevents prosecutors from showing a jury any evidence of prior abuse.
Sierra's death tore the Carpenter family apart, putting relatives on the witness stand before television cameras to talk about the woman's mothering. More than one said Carpenter -- whether or not she hurt Sierra -- did put the child at risk for abuse.
Carpenter has remarried and had another child, a girl now almost 9 months old.
Davis contends that prosecutors want to blame Sierra's death on Carpenter because they failed to win a conviction against her then-boyfriend, Brian Rutherford.
Prosecutors maintained all along that even if Rutherford had been convicted, Carpenter knew that Sierra was being hurt and did nothing to stop it.
Carpenter's case shows some of the difficulties prosecutors face in proving guilt when children die of abuse, and the challenge defense attorneys face in keeping the focus on the law and not letting emotion take over.
Testimony in Rutherford's trial centered on the autopsy finding that bleeding in Sierra's brain could have been weeks or months old.
In hearings leading up to Carpenter's potential trial, prosecutors have worked to demonstrate a "pattern of abuse" they believe the mother should have stopped.
Davis has fought to keep much of that evidence from the jury, writing that it would prejudice them against his client when the indictment deals only with the few days leading up to Sierra's death.
Carpenter's mother, Sue Petty, testified that she cared for the toddler for two days before dropping her off with Carpenter and Rutherford. She said the girl then had a single bruise on her forehead.
Two days after Sierra's April 27, 2006, death, investigators named Rutherford and Carpenter as "persons of interest." They asked Carpenter to take a polygraph test over Sierra's abuse. She passed.
Nearly a year later the pair were charged: Rutherford with murder and a sentence of life with the possibility of parole, Carpenter with neglect and up to 25 years in prison.
When Rutherford went to trial in November 2008, his defense team heaped all the blame on Carpenter.
"It's important to punish the right person, isn't it?" defense attorney Myrlene Marsa asked the jury during opening statements. "The issue is about who did it."
The defense called witnesses who testified that the teen mother mistreated the toddler, jerking her around, thumping her on the head. Other witnesses said they couldn't believe Carpenter would hurt her child, but they blamed her for leaving the girl in Rutherford's care.
When Carpenter testified, she admitted she would drive Sierra around in a car while high on methamphetamine and marijuana.
She told the jury she had done many things she wasn't proud of but had never harmed her daughter.
At the end of a two-week trial, the jury took less than an hour to acquit Rutherford.
Then prosecutors began preparing for Carpenter's trial.
Davis objected and filed documents saying so. He had expected that since his client had cooperated, testified against Rutherford for the prosecution and opened herself up for such deep public scrutiny, that the charge against her could be dismissed.
In the years since, Davis has battled to obtain what he considers a fair trial for his client.
He has sought to limit photographs, recorded interviews and certain experts' testimony from reaching a potential jury.
Hamilton County Criminal Court Judge Don Poole has considered each motion, balancing the efforts by Davis and prosecutor Neal Pinkston, who has taken over the effort to convict Carpenter.
University of Tennessee law professor Dwight Aarons, who specializes in criminal law, said the work in the Carpenter case is typical of an aggressive defense attorney and an equally committed prosecutor attempting to build their best cases through evidence.
The riskiest outcomes occur when a case gets before a jury, he said.
"Unless you have somebody at the scene who says this is what happened, then you're just left to infer from [evidence]," Aarons said. "Those are just guesses; they're educated guesses, but just guesses at what happened."
That's what makes pretrial work so crucial.
"Most trials are won or lost before the first juror is sworn in," Aarons said. "To some extent, to have a trial is a failure."