People v. Williams (2008)

Appellate Court of Illinois, First District, Third Division · 2008 · Evidence

385 Ill. App. 3d 359 (2008)

Updated August 22, 2026

EvidenceExpert testimonyDNA evidenceChain of custodyConfrontation ClauseSentencingRule 703expert basis testimony

Facts

A sexual assault kit containing the victim's blood sample and vaginal swabs was collected, sealed, secured, and sent to the Illinois State Police crime lab. The crime lab tested the swabs for semen, sent the sealed kit to Cellmark, an accredited outside laboratory, for DNA profiling, and later received it back; a separate crime lab scientist generated the defendant's DNA profile from a sealed blood sample. Crime lab expert Sandra Lambatos reviewed the results from the semen testing, the defendant's blood testing, and Cellmark's DNA profile data, made her own interpretations, and concluded that the semen profile matched the defendant. The defendant argued that the State failed to lay sufficient foundation for Cellmark-based testimony, failed to establish chain of custody while the kit was at Cellmark, and violated confrontation rights because no Cellmark analyst testified.

Issue

Whether the trial court abused its discretion by admitting Lambatos's DNA opinion testimony when she relied in part on Cellmark's testing even though she did not personally perform those tests and no Cellmark analyst testified. Also, whether testimony based on Cellmark's report violated the Confrontation Clause, and whether a 60-year sentence may run consecutive to a natural life sentence.

Rule

An expert may testify to an opinion based on facts or data not in evidence if they are of a type reasonably relied upon by experts in the field. When an opinion relies on a mechanical or electronic device, some foundational proof must show the device was functioning properly, but the expert need not personally determine instrument reliability if the basis is the sort experts reasonably rely on; challenges to sufficiency or reliability are tested on cross-examination and ordinarily affect weight rather than admissibility. For chain of custody, the State must show reasonable measures making tampering, substitution, or contamination improbable, but need not call every custodian or exclude every possibility absent evidence of actual tampering. Testimonial statements used only to explain the basis of an expert's opinion, rather than for the truth of the matter asserted, do not violate the Confrontation Clause.

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One of 10 multiple-choice questions for this case. Pick an answer to see why.

In a robbery trial in Chicago, the State calls Dana Mercer, a forensic DNA analyst at the state crime lab. Dana testifies that an accredited private laboratory in Ohio generated a DNA profile from saliva on a ski mask, that the laboratory's methods are generally accepted in the scientific community, and that analysts in her field routinely rely on such profiles. She reviewed the raw profile data along with the defendant's known sample and made her own comparison, concluding the profiles matched.

If the defendant objects that Dana may not testify because she did not personally perform or observe the private laboratory's testing, how should the court rule?

Explanation. The testimony is admissible. The majority held that a qualified expert may rely on nontestifying analysts' results if they are of a type reasonably relied upon by experts in the field, and the expert reviews the data and forms her own opinion. The absence of personal observation of the outside lab's testing does not itself bar admissibility.