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DuPage County Sheriff

James Mendrick

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About Us


Crime Laboratory

The mission of the DuPage County Sheriff's Crime Laboratory is to provide quality and timely forensic science services to the criminal justice system of DuPage County. This mission is achieved by meeting these objectives:

  • Maintaining proper facilities for casework and receipt of evidence
  • Employing and training highly qualified scientists
  • Adhering to scientifically accepted procedures and laboratory quality assurance standards
  • Reporting analytical findings coherently and efficiently
  • Clearly articulating analytical findings in a court of law.

Scientists working in the lab adhere to a complex quality control system, have access to state-of-the-art- instrumentation, first class training opportunities, up to date literature, and a large network of professional peers with whom to exchange information. Collectively, these resources enhance the scientific reliability and accuracy of information reported.

In 2006 the Board of Directors of the American Society of Crime Laboratory Directors Laboratory Accreditation Board unanimously voted to grant ISO certification to the laboratory making it the only county crime lab in Illinois accredited under ISO's international quality assurance standards of excellence, and only the second county based lab in the nation so recognized. The laboratory successfully continues to maintain its accreditation status.

The crime laboratory employs forensic scientists in the following disciplines: controlled substances, latent prints, and forensic biology/DNA.

Chemistry Section

Using microscopical, instrumental and chemical techniques, the lab is able to identify the presence of controlled substances in solid and liquid samples.


This section is responsible for the development and comparison of latent fingerprints.

Scientists in this discipline use AFIS (Automated Fingerprint Identification System) to match unknown fingerprints to known prints contained in the AFIS database. 

Forensic Biology/DNA

Forensic biology involves the examination of evidence for the presence of hair and body fluids such as blood or saliva. Recovered DNA profiles are searched in CODIS, a national DNA database containing profiles of convicted offenders and unknown DNA profiles from biological evidence recovered at a crime scene.