Forensic Unit

Property Room

The property room of the Police Department has two primary functions.  One is to maintain what is called a "chain of custody" for evidence in criminal cases.  The court rules require that evidence be stored in an area not accessible to anyone but a few, authorized Police Department personnel.  Any movement of the evidence to a detective investigating the crime, or to an officer that needs it for court, etc., must be documented.  To fail to perform either of these functions could cause the evidence to be inadmissible in court.

The second function is to protect any property taken into the custody of the Police Department.  Our obligation is to protect the value and integrity of property.  Beside crime evidence, it also includes lost objects turned in to the Police Department because the owner is unknown.  We have had such things as large amounts of money, diamond rings worth several thousand dollars, cremated remains, keys, etc.

The volume of property and evidence coming into the Department has steadily increased.  This is due to an increase in criminal incidents as our population grows, new Illinois statutes that require certain types of evidence to be stored for many years, and the ability to obtain forensic evidence from items that previously yielded none.  Responsibility for much of this increase is due to the improvements in DNA extraction and processing technology.


Crime Scene Investigation

The forensic capabilities of the St. Charles Police Department has grown as the technology has changed and expanded over the years.  Evidence is collected from crime scenes ranging from theft to homicide.  That evidence, combined with the investigative skills of the patrol officers and detectives, helps to ensure successful prosecutions of the offenders.

The department submits its evidence to the Illinois State Police Crime Laboratory in Rockford, IL.  The forensic scientists there process the evidence collected.  The goal of both the police and scientists is to obtain irrefutable facts about the commission of the crime and the offender.  Physical evidence is unbiased and objective.  It can place an individual at the scene of a crime or show that the person was not at the scene.  It helps to determine guilt or innocence.  The primary goal of physical evidence is to show the truth.

Various pieces of equipment and advanced training of personnel are used to properly collect and process the evidence.  We have the potential to develop fingerprints on almost any type of object.  From bottles, cans, cups, and magazines, to paper, cardboard, wood, rocks and human skin.  Processing utilizes superglue fumes, chemicals, fluorescing dyes and powders.

A forensic light source allows investigators to view objects under various wavelengths or colors of light.  Some evidence has natural fluorescing capabilities under various light colors and can only be seen visually by using the correct wavelength.  Injuries to the body can sometimes be visualized with the correct light but would not be able to be seen by the naked eye in normal light.  The light is bright enough to allow evidence to be observed that might otherwise not have been detected.  This would include such things as hairs and fibers used to identify persons at the scene.

A superglue fuming chamber allows the vaporized fumes of superglue to be deposited onto fingerprint residue on objects.  The fingerprints turn into a light gray color and can be collected by various means, including transferring the powder print onto an adhesive ‘lifter’ and spraying the developed print with a fluorescing dye allowing the print to be photographed under ultraviolet or other light frequency.

DNA is collected through various methods, from body fluids that have been deposited at the crime scene to skin cells that have been deposited on objects handled by the offender, from drinking glasses to eyeglasses and contact lenses; from steering wheels to stamps and baseball caps.  We even developed a DNA profile from human feces that was deposited by the offender.  The list is endless.

We have kits that detect and collect gunshot residue from the hands of a person that has recently discharged a firearm.  Other kits make impressions of the pry marks left by tools, and still more that will pick up a dusty footprint.  Casting material can make an impression of a footprint or tire track, including those in snow.

The more evidence we collect, the greater the chance to identify and prosecute the criminals.

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updated Sep 27, 2018

Criminal Investigations Division

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