Forensic Services

The Crime Scene Response Unit is staffed 24/7 and is responsible for processing all crime scenes within the City of Chandler. The duties include photographing, documenting and sketching of scenes, as well as recognizing, collecting and preserving all types of physical evidence. The Crime Scene personnel respond to approximately 4,500 calls each year ranging from vehicle burglaries, minor accidents, assaults, death investigations, etc.

Crime Scene Protocols

Toxicology is the study of the effects of chemicals on biologic systems.  Forensic Scientists that work in the Human Performance Forensic Toxicology (Blood/Urine Alcohol) section analyze blood to determine a blood alcohol concentration and the presence of other volatiles.  Urine can also be analyzed qualitatively to determine if ethanol was contained in the sample.  Ethanol concentration and the presence of other volatiles in bodily fluids and liquids is performed by using Headspace Dual Column Gas Chromatography with Flame Ionization Detection (GC/FID).   Forensic Scientists that perform Human Performance Forensic Toxicology (Blood/Urine Alcohol) analysis are required to have a Laboratory Analyst’s Permit that requires re-certification on a yearly basis. 

The Human Performance Forensic Toxicology (Blood/Urine Alcohol) section also analyzes liquids/liquors to determine if ethanol is present.

The Human Performance Forensic Toxicology (Blood/Urine Alcohol) analysts also testify in court to explain and support their finding and to explain the pharmacokinetics and pharmacodynamics of ethanol and ethanol effects on human performance.

Forensic Alcohol Protocols

Forensic Scientists that work in the Seized Drugs Unit analyzes pharmaceuticals, illicit drugs, plants, related chemicals and drug paraphernalia.  The Chandler Police Department Forensic Services Section can conduct drug analysis for marijuana/cannabis, methamphetamine, heroin, cocaine/crack, ecstasy (MDMA) tablets, LSD, mushrooms, PCP, steroids and prescription drugs.  The Forensic Scientists perform preliminary analysis using chemical color tests, pharmaceutical identifiers and/or the TruNarc device.  Identification of controlled substances is performed by using a Gas Chromatograph/Mass Spectrometer (GC /MS), Fourier Transform Infrared Spectrometer (FTIR) and/or macroscopic/microscopic examinations.   They also provide expert testimony is court proceedings to explain and support their findings. 

The Seized Drug Unit also conducts a Field Drug Testing class to train officers on the use of field drug testing kits. 

Seized Drugs Protocol

The Forensic Scientists analyze fingerprints and palm prints recovered from crime scenes. Their main goal is to identify the person that left the print. Human friction ridge skin is found on the fingers, palms and feet.  Friction ridge skin can be used as a means of identification because human friction ridges are unique and persistent, human friction ridge skin arrangements are unique and persistent and a positive identification can result from comparisons of friction ridge skin impressions containing sufficient quality (clarity) and quantity of friction ridge detail.  Forensic Scientists that conduct latent print comparisons use AFIS (Automated Fingerprint Identification System) to search prior records in the database to determine the closest candidates to the entered print.  Forensic Scientists that work in the latent print discipline also perform comparisons using the analysis, comparison, evaluation and verification process to try to determine an identification of a fingerprint.  The Forensic Scientists also testify in court to explain and support their findings. 

Friction Ridge Comparison Protocols

The Latent Print Processing section develops latent (hidden) prints on evidence that is submitted to the Chandler Police Department Forensic Services Section.  An initial surface examination is first conducted on the evidence by using white light, a forensic light source or RUVIS (Reflective Ultra Violet Imaging System).  The evidence is then processed by following a sequence guide that directs the forensic scientist to the particular processing techniques that will be used to develop the print depending on the type of evidence that is submitted.  Some examples of types of evidence are porous, non-porous or blood.  The Latent Processing section uses many processing techniques such as cyanoacrylate fuming, fluorescent dye stains, ninhydrin and powder to develop and secure the latent print.  Latent print images are then captured through photography or scanning.

Latent Processing Protocols

The Crime Scene Technicians (CST’s) operate the Arizona Automated Fingerprint Identification System (AZAFIS) This system serves as the central repository for fingerprint identification records relating to persons arrested throughout the state. The CST’s process fingerprints and palm prints of subjects fingerprinted for employment, arrested, or taken into custody from booking facilities throughout the city. These fingerprint images are captured electronically by a Livescan device, which creates a fingerprint record. This record is then transmitted electronically to Department of Public Safety (DPS), which passes information back and forth between different databases maintained by the Department of Justice (DOJ) during the processing of fingerprint records.

The Crime Scene Technicians process fingerprints and palm prints for the purpose of establishing positive identification and creating an individual’s criminal history record. CST’s perform quality control on images and finger sequence errors for all fingerprint records as needed. Verification is completed by a second CST on all possible matches for ten print to ten print searches. All ten print and palm print arrest records are searched through AFIS against the unsolved latent print database in an attempt to identify suspects that leave their prints at crime scenes.

AFIS Ten Print Protocols

Quality Assurance Manual

Chandler PD Career