Weld County

Sheriff's Office

Leading with responsive, innovative and cost effective services.

Regional Crime Lab

crime_lab1 The Greeley/Weld County Forensic Lab provides several scientific services to the Weld County Sheriff’s Office and the Greeley Police Department. These typically include crime scene  investigation, fingerprint comparison, digital evidence collection and analysis, and chemical analysis services. The chemical analysis services have been accredited by the American Society of Crime Laboratory Directors / Laboratory Accreditation Board (ASCLD/LAB) since 1991.


crime_lab4Crime scene investigators (CSI) work with Deputies and Investigators at major crime scenes where the CSIs document, collect, and preserve all the evidence. They are responsible for the diagramming of crime scenes and correct accounting for all the collected evidence. The quality of their work and their testimony in court is crucial to the admissibility of the gathered evidence.

Footwear and tire impression evidence is commonly found at crime scenes. Crime scene investigators will document these impressions through photography and casting or lifting techniques. It is the job of the expert in the Greeley/Weld County Forensic Lab to compare shoes or tires submitted to these photographs, castings and lifts to determine if they made, could have made, or did not make the crime scene impressions.



crime_lab3 Fingerprint comparison is one of the oldest recognized forensic specialties. However, before a comparison can be made, fingerprints must be found, revealed, and documented. Many specialized methods have been developed to reveal fingerprints on the many surfaces needing fingerprint processing. In addition to the fingerprint powders that are available, there are many chemical methods used to treat surfaces. Most of these chemical methods are used in conjunction with an "alternate light source" to enhance the detail and contrast of a fingerprint on a surface. Prints revealed with powders are "lifted" with tape and placed on a contrasting background for examination. Prints revealed using other methods must be photographed to scale, and the photos used by the examiner for comparison. A fingerprint comparison expert must then judge the quality and detail in an unknown print before a comparison can be made. Using high-resolution digital photography and image enhancement software, an examiner can digitally "remove" things like repeating patterns or interfering colors on the surface of the print and then the fingerprint is photographed to produce a better quality image.”


Digital evidence is like fingerprints. Investigators don’t know what they have until an expert examines their evidence. The digital evidence expert must first preserve the original evidence by making an exact copy or "image" without altering the original. This copy is then subjected to file searches for evidence of a crime, and file restoration, if the suspect may have deleted files that are evidence. Any digital device can be "examined", not just computers. The need for this service to law enforcement has grown dramatically as digital devices are used by all of society as well as criminals.


Chemical analysis services primarily use infrared spectroscopy (I.R.) and gas chromatography/mass spectroscopy (GC/MS), as well as microscopic examinations and photography where appropriate. The majority of cases requiring chemical analysis involve identifying controlled substances (illegal drugs). Suspected arson cases require analysis for ignitable liquids that can be used to accelerate the progress of a fire. When investigating clandestine drug labs, several organic and inorganic samples are present. The chemical analysis section will assist in both the processing of these crime scenes as well as the analysis of the samples taken. 

A recent addition to the forensic services in Northern Colorado is the combining of resources from several of the larger agencies to better handle the needs of the criminal justice community.  Currently, a partnership exists that has personnel jointly working casework in the above-mentioned disciplines.  In addition, other disciplines such as DNA analysis are being done by our personnel at host sites like the Colorado Bureau of Investigations Denver laboratory while we plan a new facility here in Northern Colorado that will house a full service forensic laboratory.

The services provided by the highly trained personnel in the Greeley/Weld County Forensic Lab are as comprehensive in the specialty areas described above as larger labs. The goal of the lab is to provide quality services that meet the needs of the criminal justice system in Weld County. Laboratory examinations and analysis carried out with integrity and technical competence will help exonerate the innocent as well as help convict the guilty.

Contact Information

Greeley / Weld County Forensic Laboratory
Ronald Arndt - Lab Director
phone:(970) 356-4015 x 3638