Enemy Within III: Trial and Verdict

Having celebrated her her last two birthdays behind bars, Valessa had plenty of time to hear what most people thought of her.

But it was the jury she had to face on charges of killing her own mother that Valessa, then 17, was most worried about. Valessa was relying on her defense lawyer, Deeanne Athan, to convince a jury she was not a monster. In her opinion, John Whispel and Adam Davis were the murderers.

Athan's defense strategy was to paint Davis as a manipulative, dangerous drug dealer and Valessa as the young, vulnerable child under his spell.

On Nov. 3, 1999, a year and a half after Vicki Robinson was murdered, the youth who cut her throat went on trial. Not only did prosecutors have Davis' confession to the murder, they also had John Whispel.

Whispel agreed to testify against his best friend in exchange for a plea bargain. Davis was found guilty. Six weeks later, Davis - abandoned as a child - was sentenced to death.

Then it was Valessa's turn to face a jury. As her trial got under way, the sides were quickly drawn. On one side were Vicki Robinson's parents and Valessa's grandparents.

"I don't feel she should be able to walk the street again," said her grandfather, Art Klug. On the other was her father and sister. "One thing my child is not, she's not a murderer," said her father Chuck Robinson.

To influence the jury, the defense presented a madeover Valessa for court. "I want her to look like the young, sweet, charming, engaging teen-ager that she is," lawyer Deanne Athan explained.

Athan hoped to prove that Valessa was in another room, drugged on LSD, when Davis and Whispel killed her mother. There was no physical evidence against Valessa - no fingerprints, no DNA. So the prosecution built its case on Valessa's initial confession and the eyewitness account of star witness Whispel.

Whispel opened with a bombshell: "All of a sudden she gets happy, smiles, jumps up and down and says,'Let's kill my mom.' Me and Adam, we're shocked; we're, like, what? And she's, like, 'let's kill my mom,'" he testified.

He declared that Valessa not only wanted her mother dead, she also helped kill her. Whispel told the prosecutor that Valessa sat on her mother's legs, held her down.

Valessa did not take the stand. So Athan built her defense by attacking Whispel's credibility. Athan reminded Whispel that his story had changed since he first confessed to police.

After deliberating for almost 18 hours, more than three days, the jury finally reached a verdict: third-degree murder. Seventeen-year-old Valessa Robinson could have been sentenced to life in prison but instead received 20 years.

While Valessa's lawyer is appealing this conviction, there has been no decision since 48 Hours first aired this story more than a year ago. If it stands, Valessa will be in prison at least until her early 30s. Lawyers for Adam Davis are appealing his conviction as well.

Her grandfather Arthur Klug said he didn't want to see Valessa get out on parole.

Her father Chuck Robinson said the verdict was the best that could have happened for except acquittal.

With a mother murdered, and a daughter behind bars, are there any lessons to be learned from a tragedy that makes so little sense? Here's what some of those close to the case told 48 Hours.

When Valessa was asked what she wished her mother had done differently in raising her, she said, "I wish that she'd disciplined me more. I wish she had laid down the rules."

"Vicki just got tired of disciplining her because she was very willful," said public defender Deeanne Athan. "And Vicki just said,...,'I give up; do what you want to do.' And basically, Valessa did whatever she wanted to do."

Her father, when asked if he felt as though he let Valessa down, said he did: "I think had that divorce not happened, Vicki would still be alive, and Valessa wouldn't be in jail. And Adam Davis wouldn't be anywhere near my family."

What should a parent do with a teen who is doing drugs and with a boyfriend like Adam?

Valessa's answer: "They need to be there for them, see that there's something wrong going on," Valessa said. "Get them away from the crowd that they're around."

That, of course, was Vicki Robinson's intention. But it was too little too late.