On the night of Dec. 6, 1991, four teenage girls were found murdered in an Austin, Texas I Can't Believe It's Yogurt! shop. They had been executed and their bodies stacked and burned. The crime scene was described by the lead detective as "wholesale carnage."
The crime scene was contaminated by the firemen and emergency personnel. Water used to put out the flames also washed away evidence. Despite numerous leads and false confessions, it took investigators years to come up with any answers in the case.
On the night of the murders, Sarah Harbison, 15, top left, and Amy Ayers, 13, top right, had dropped by the yogurt shop to help Sarah's sister, Jennifer, bottom left, and Eliza Thomas, both 17. The girls had been working the late shift that night.
Amy Ayers was the youngest of the four victims and had been shot twice. "I can see her riding, and just taking off across a pasture on a horse and enjoying it because she loved it so much," her mother, Pam Ayers, told "48 Hours Mystery" correspondent Erin Moriarty.
Eliza Thomas, 17, was working the late shift at the I Can't Believe It's Yogurt! shop in Austin, Texas. "Unless you've been through it, you just cannot imagine how bad it is to have lost a child and to have lost one to violence, too," said Eliza's mother, Maria Thomas.
Soon after the yogurt shop murders, detectives questioned four teenage boys. Maurice Pierce, top left, was arrested for having a gun at a local mall. Forrest Welborn, top right, Michael Scott, bottom left and Robert Springsteen were the friends Pierce was hanging out with that day. They were all questioned and released.
In 1999, eight years after the murders of the four girls, Maurice Pierce, Forrest Welborn, Michael Scott and Robert Springsteen - the same four individuals first questioned as teenagers in 1991 - were arrested and charged with capital murder.
During his interrogation by Austin, Texas detectives on Sept. 9, 1999, Michael Scott confessed to participating in the 1991 murders. "I remember looking at this girl. I hear the gun go off... I only pulled the trigger once. I hear another gun go off. I think I hear a total of five shots."
After hours of questioning in 1999, Robert Springsteen also confessed. He told detectives he not only killed one of the girls, he said he raped her. His lawyer would argue that the confession was coerced.
Forrest Welborn, 23, right, leaves the Travis County Jail on Dec. 10, 1999, after his release on bail. A day earlier, a judge ruled he must stand trial as an adult in the case. Welborn was 15 at the time of the 1991 murders. When he was questioned in 1999, he denied knowing anything about the crime. Investigators tried twice to indict him, but the case against him was dropped, as was the case against Maurice Pierce.
Michael Scott, left, and Robert Springsteen were each tried for murder and both were found guilty of the yogurt shop murders. Ten years into their life sentences, both verdicts were thrown out and the men were granted new trials.
On Oct. 28 2009, after serving 10 years of their sentences, prosecutors dismissed all charges against Michael Scott, shown in an undated photo, and Robert Springsteen. The news came after the Travis County D.A. was unable to link unknown male DNA from one of the victims to either of the men.