A DNA sample kit (AP)

Kits for processing crime scenes come in different sizes and contain instruments and implements for different purposes, from collecting latent fingerprints to vacuuming trace evidence.  They can be purchased commercially, or investigators can put together their own version.

Ethan Jensen, a Field Training Officer in Nebraska who specializes in defensive tactics, purchased two large fishing tackle boxes to use as crime kits.  Into them he puts crime scene tape, a flashlight, logbooks, pens, a camera, extra film, paper sacks, tongue depressors, rubber bands, a sketch pad, disposable clothing and masks, gloves, string, measuring implements, fingerprinting items, casting items, orange flags, butcher paper, rape investigation kits, field test kits for drugs, blood draw kits, and emergency phone numbers.  Taped to the inside lid is a conversion chart for distance, weight, and volume.  With living victims in mind, he puts in a few extras:  "I always keep a small packet of written materials, which includes pamphlets for domestic abuse victims and the telephone numbers of local rape counselors.  There are usually a couple of stuffed animals in the trunk to give to child victims."

Preparation for long hours at a crime scene is key, so whatever is used up must be replaced immediately.  One kit kept in the crime scene van contains tools like a hammer, pliers, a saw, and a screwdriver for removing evidence that may be on part of a structure.  They may also have an alternative light source, like Luma-Lite, with a generator, and many investigators also bring metal detectors.

The specific-use kits listed below have standard contents as well.

1)  A basic fingerprinting kit might contain the following:

• fingerprint powder
• fiberglass dusting brushes
• camelhair brushes to clean dust from prints
• clear lifting tape and dispenser, and/or lift tabs
• latent print cards and elimination print forms, with markers
• ink pad for taking prints on the spot
• magnifying lens, scissors, tweezers, scalpel
• evidence rulers of different lengths
• evidence seals, tags, bags, and boxes of different sizes
• disposable gloves

2) A casting kit for tire and footprint (from foot or shoe) impressions would include:

• casting powder
• casting compound
• a water container and mixing bowl
• mixing implements
• casting frames of different sizes
• rubber lifters
• a fixative
• snowprint wax spray, which helps to take castings from snow

3) For shootings, an investigator might use a laser trajectory kit, which helps to assess projectile paths at a crime scene.  The kit includes:

• a laser pointer
• an angle finder
• a centering cone
• penetration rods
• a tripod mount

4) Trace evidence collection requires different procedures for different types.  To collect broken glass, for example, the CSI may only need tweezers and an evidence container.  For soil samples, fiber, and hair too small to see clearly, they may use a trace evidence vacuum that comes equipped with special filters.  Each kit comes with a knife for scraping dried evidence, and a wide variety of containers for different types of evidence, such as metal cans for paint chips or glass.  (Even seemingly insignificant items should be collected.  A photo receipt found in John Wayne Gacy’s wastebasket proved that a missing boy had been in his home and allowed investigators to get a search warrant.)

There are also special kits for gunshot residue, for detecting the presence of blood that may have been wiped clean, for presumptive blood tests, for bodily fluid collection, for collecting bug samples, and for assessing potentially hazardous situations

For rape victims, there's a sexual assault kit that contains:

• evidence envelopes for such things as fingernail scrapings and foreign substances
• a sexual assault incident form
• authorization form
• oral, vaginal, penile, cervical, and anal swaps
• smear slides with appropriately-labeled mailers
• blood collection tubes
• instructions for both male and female victims
• pubic hair combs and mailers
• bags for pulled head hair and pubic hair
• scissors for cutting hair close to root (in the case of people who object to hair being pulled from the root)
• evidence seals with biohazard labels.

In cases of extreme decomposition of a corpse, modified gas masks (anti-putrefaction masks) may be needed.  These are generally kept in the vehicle rather than in a kit.

Whatever evidence is collected gets correctly labeled according to the case number, and goes right to the lab for processing.

While evidence is being collected, another forensic professional is processing the crime scene via photographs.  Getting clear photos can be crucial to proving a case, so let's look at the photographer's method.