Expert: No DNA match for Rivera

The DNA taken from Holly Staker's body and several samples of genetic material found in the apartment where she died do not match Juan Rivera, a scientist testified Wednesday.

There also is no match to the DNA samples taken from close to 30 people in the weeks following the 11-year-old's 1992 slaying, he said.

The testimony of Alan Keel came in the 13th day of Juan Rivera's third trial for the rape and murder of the Waukegan baby sitter.

Rivera, 36, has been convicted and sentenced twice to life in prison, but new trials were ordered after each conviction.

Keel said he tested the evidence at Forensic Science Associates in Richmond, Calif., in 2005 on behalf of Rivera's defense team.

The fact that there was no match to Rivera's DNA in any of the tests prompted Lake County Circuit Judge Christopher Starck to order a new trial the following year.

Defense attorneys claim the lack of a DNA tie to the crime means that Rivera is not the girl's killer, but prosecutors counter that it is possible the girl had sex with someone else days before her death.

Last week, Holly's twin sister, Heather Staker, testified that the sisters had their first sexual experience when they were 8 years old.

Keel testified Wednesday that it was his opinion that the semen taken from Holly's body was left just before her death, based on his estimation of the number of sperm cells found in the sample he tested.

During cross-examination, Assistant State's Attorney Michael Mermel questioned the reliability of DNA testing on the material that had been collected 13 years before it arrived in Keel's laboratory.

Keel admitted that he was not familiar with the all of the labs the material had passed through and the safeguards each lab had in place to prevent contamination of the material.

Keel also said he was aware that some genetic evidence tested by another laboratory in the early stages of the case had been contaminated with the DNA of the person doing the testing.

Mermel also challenged Keel's theory that the DNA taken from Holly's body was deposited shortly before her death by showing him a number of photographs of sperm cells that showed signs of deterioration.

Earlier in the case, another DNA expert said he could not rule out the possibility that the DNA found in Holly could have been there for up to four days before her death.