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Witnesses debate probability of DNA matching Luna
By Joseph Ryan | Daily Herald Staff
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Published: 5/3/2007

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Depending on which witness is talking in the Brown's Chicken murder trial, the crime scene evidence tied to Juan Luna's DNA could only match 1 in 2.8 trillion other people or it may be the same profile as 1 million other Americans.

The numbers could matter to jurors in deciding whether Luna helped shoot to death seven people in the Palatine restaurant on Jan. 8, 1993. And the jury got another dose of numbing scientific testimony Thursday as prosecutors tried to rebut a defense witness who cast the critical DNA evidence in doubt.

Ranagit Chakravorty of the University of Cincinnati's Center for Genome Study testified that the DNA found on chicken bones at the restaurant was likely Luna's.

Both defense and prosecution experts agree that Luna is not excluded from the DNA sample, which contains at least two contributors. Chakravorty said that fact means Luna is at least 234 million times more likely to be one of the contributors than any random person.

Put another way, Chakravorty said a random person picked off the street would have a 99.99999 percent chance of being excluded from the DNA sample. Luna had that same chance, he added, but wasn't excluded.

That may seem to contradict an earlier defense witness who told the jury more than 1 million U.S. people could have the same DNA profile prosecutors are using.

Chakravorty directly disputed that testimony. The witness, Karl Reich of the Independent Forensics of Illinois lab, used a recent study of DNA from 220,000 Illinois prisoners to make his conclusion. He also said the mishandling of the sample made the results worthless.

A study of DNA data from the prisoner database found 903 matches on nine individual points, the same number as in the Luna sample. Authorities usually use 13 match points, but the Brown's Chicken sample didn't contain enough of a sample to cover that number.

Reich said prisoner data was more reliable than a database using a few hundred subjects such as the FBI database that produces the 1 in 2.8 trillion figure used by prosecutors.

Chakravorty said using the Illinois prisoner database is wrong because it does not account for relatives in the population or race like the FBI database does.

The defense has taken steps to also knock down the DNA evidence as tainted and mishandled.

An expert has testified he was directed by investigators to handle the chicken bones without gloves and that he ripped meat off the bones to determine what chicken pieces they were from. The chicken bones were also frozen and thawed several times before testing and authorities lost the swabs that produced the DNA results.

The bones were found in a near-empty trash can at the restaurant two days after the murders. They are believed to be from the last meal ordered the night of the killings, Jan. 8 1993.

A napkin found with the trash contained a partial palm print prosecutors say also matches Luna. Defense attorneys also dispute the handling and validity of that print, which came from a dime-size area just below one's pinkie finger.

Testimony in the case is wrapping up Thursday after about three weeks of defense and prosecution witnesses. Closing arguments are currently scheduled for Wednesday.

Prosecutors alleged Luna and his high school pal Jim Degorski shot and killed seven at the Brown's Chicken and then got away with it for nearly a decade by intimidating two friends who they told of the crime.

Degorski and Luna are being tried separately and both could face the death penalty if convicted. Both have pleaded not guilty.

The prosecution also had two of Luna's old friends testify that he excitedly described the crime to them shortly after it occurred. Perhaps more importantly, they have played jurors a 43-minute videotaped confession from Luna.

The defense, meanwhile, has tried to discredit the witness as drug users and alcoholics. The two didn't come forward with their stories until 2002, when Luna first surfaced as a suspect despite being interviewed by police twice before as a previous Brown's Chicken employee.

The defense has also played another man's videotaped confession to the crime. That forced prosecutors to admitted Palatine police could get an innocent man to confess. The defense says Luna's confession was coerced after 19 hours of interrogation.

The victims include restaurant owners Lynn and Richard Ehlenfeldt and employees Michael Castro, Guadalupe Maldonado, Marcus Nellsen, Thomas Mennes and Rico Solis.