Investigate a crime scene from your desktop! Begin your investigation by reading the summary of the facts and continue by visiting Forensic Services and having evidence processed. Keep investigating to determine the identity of your suspect. Navigation buttons at the bottom of each page will allow you to move forward, backward, or start over -- OR -- use the navigation links on the right side to jump to the page of your choice.
The following pages represent the scene of a violent, but fictitious crime. The individuals depicted are actors. No criminal involvement should be inferred by their participation.
At 1:54 am on October 18 officers responded to 133 N. Morris, Mesa, AZ. in reference to a 911 call by a neighbor who heard shots fired at this address. When officers arrived at the scene they found one deceased male subject and evidence of a crime. The officers secured the scene and notified Homicide detectives and the Crime Scene Unit.
A canvas of the neighborhood by officers located two witnesses who had each seen a suspicious looking man leaving the area just after the shots were fired. Working with the two witnesses individually a Crime Scene Technician completed two separate composite sketches.
The first witness said that she was looking out her window when she saw a nervous looking man (suspect #1) running from the direction the shots had been fired and driving away recklessly in a blue four-door car.
The second witness heard the shots and when he walked out onto his porch he saw a man (suspect #2) run through his yard and jump into a silver SUV. The man was limping and looked very agitated.
Detectives soon found out that men matching the description of both suspects had been pulled over and arrested for DUI within a couple of miles of the crime scene.
- Suspect #1 was arrested when he was found driving the wrong way on a freeway on-ramp. He was determined to be driving with a revoked license and had multiple warrants for failure to appear at previous court dates. Suspect #1 was not wearing shoes when arrested.
- Suspect #2 was arrested after he was observed weaving and running a red light. When arrested, Suspect #2 only had one shoe on and had a wound on his leg that he claimed he had gotten when he tripped and fell in an alley. Additionally, a loaded firearm was found under the driver's seat in his silver SUV.
The Crime Scene Unit photographed the scene, collected evidence, and processed for latent prints. Overall, midrange, and close up photographs were taken of the items of evidence marked with placards. Each item with a numbered placard was collected as evidence and each lettered item was swabbed for DNA. All items were packaged and submitted to evidence for impound.
The scene was then processed for latent fingerprints using Black and Magna Powders. Latent fingerprints were detected, lifted and submitted to the Latent Print Unit for further analysis and comparison to suspects #1 and #2.
Numbers are used for items collected from the scene. Letters are used when a only a sample is collected.
The photo lab managed and made copies of the photographs taken at this scene. Digital photos were downloaded, logged in, verified, and added to the department's imaging system. Using this system, detectives were able to view photographs of the scene from their desk and order the reprints, enlargements, and photo CDs they needed during the investigation and trial.
The Firearms Unit analyzed two cartridge cases, one bullet (projectile), and one firearm recovered from the crime scene. They also analyzed another firearm recovered from suspect #2. The Firearms Unit compared the bullet and cartridge cases from the crime scene to test fires from the firearm collected at the scene (item marked #6). It was excluded as having fired the bullet/cartridge cases.
A serial number restoration was also completed on this firearm. Running the serial number through NCIC revealed that the weapon was stolen six months earlier. The Firearms Unit compared the bullet and the cartridge cases from the crime scene to test fires from the firearm found on suspect #2. It was determined that the bullet and both cartridge cases were fired from this firearm.
The Firearms Unit also identified the shoeprint left at the scene to a shoe found on suspect #2.
Using Cyanoacrlate ("super glue") fuming, MBD dye, and black powder on the knife collected at the crime scene and Cyanoacrylate fuming, ARDROX dye stain, and black powder on both firearms, the Evidence Processing Unit developed latent prints on all three items.
Afterwards, the Evidence Processing Unit swabbed the knife and firearms and took cuttings of the cigarette butts to allow the Biology unit to perform DNA testing.
The Latent Print Unit compared the latent fingerprints developed by the Evidence Processing Unit on the firearm found on suspect #2 to the major case exemplars obtained from both suspects. A latent print found on the gun was identified to suspect #2. A latent print developed on the knife was entered into the Arizona Automated Fingerprint Identification System (AZAFIS) and was identified to the victim, John Doe.
The Controlled Substances unit analyzed the off-white substance found at the scene. The substance was found to weigh 471.7 grams and the following preliminary color tests were performed, Marquis test, Cobalt Thiocyanate test and Sodium Nitroprusside test. The results of the preliminary color tests indicated the presence of methamphetamine. The substance was then instrumentally analyzed usingGas Chromatography Mass Spectrometry(GC/MS), which confirmed the presence of methamphetamine.
Blood and urine sample were collected from the two suspects. The Toxicology Unit analyzed the blood for alcohol using Headspace-Gas Chromatography (GC) with Flame Ionization Detection (FID), which resulted in a 0.12% blood alcohol concentration on suspect #1 and a 0.18% blood alcohol concentration on suspect #2.
The Urine was screened for drugs using Enzyme-Linked Immunosorbent Assay(ELISA.) Methamphetamine and amphetamine (methamphetamine metabolite) were confirmed by Gas Chromatography/Mass Spectrometry (GC/MS) in suspect #1. Suspect #2 had negative results.
The Serology section performed phenolphthalein testing on the bloody items and tested the drinking items for the presence of amylase (a constituent of human saliva.)
The DNA section performed a Polymerase Chain Reaction (PCR) technique to obtain DNA profiles for the above items. The profile from the knife handle matched a known DNA sample from the victim, John Doe, and the blood on the knife matched the known DNA sample from suspect #2. The blood from the shoeprint and the shoe at the scene matched the victim's profile.
- Reviewed my photos
- Viewed photos
- Tested evidence
So who did it?
Suspect #2
- Suspect #2's DNA was found on the laces of the shoe left at the scene (Item #12).
- Blood on the floor (Item A) and the knife (Item #3) were found to match his DNA profile.
- Both the bullet (Item #1) and the cartridge cases (Items #7 & 8) at the scene were fired from the gun found under the driver's seat of his car.
- Fingerprints developed on the firearm from the car were identified as Suspect #2's.
- Suspect #2 had a blood alcohol level of 0.18 when he was arrested and urine was negative for methamphetamines and amphetamines.
When Homicide detectives confronted Suspect #2 with the evidence he confessed that he had gone to the victim's house in order to collect money for some drugs that he had sold to the victim. When the victim didn't have the money Suspect #2 got angry and shot the victim. The victim pulled out a knife and fought with Suspect #2 stabbing him in the leg. Suspect #2 shot the victim again and he fell to the floor. Suspect #2 then grabbed some drugs and money and ran away. Only when he got out of the car to stash the drugs and money at his house did he notice that he was missing a shoe. He was on his way to buy new shoes when he was pulled over and arrested for a DUI.