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Why Evidence Collection Materials & Evidence Storage Matter

December 5, 2017

One of the most important aspects of law enforcement is evidence collection, and every little detail can make a big difference in pursuing justice and complying with applicable laws. It may seem like common sense to place evidence into a bag for safekeeping, but it’s important to use certain types of evidence collection bags for specific types of evidence to maintain its integrity and usability in lab testing.  

This article will explain why the material used to collect evidence matters and other environmental considerations to keep in mind when storing evidence.

When Clear Plastic Evidence Bags Work Best

One example of when clear plastic evidence bags are the preferred method of storage is for fingerprints on absorbent materials. After photographing the surface with fingerprints, place the absorbent material in a plastic bag and then label and seal it with the date, your name, description, and exhibit number.

Another example of when to use plastic evidence bags is for gunshot residue from firearms. For gunshot residue, use latex gloves and moisten cotton swabs in dilute nitric acid to swab the back of the suspect’s hand. Label evidence bags properly and never place swabs in glass vials.

Spent cartridge cases, shotgun shells should also be preserved as evidence in plastic bags. This is also the best way to store glass evidence, cotton swabs with grease, metal filings, unembedded metal fragments, and paint chips.

At Superior Bag, we provide law enforcement evidence bags that are tamper-evident and made with durable clear plastic materials. These bags also have lines for documenting essential case information and evidence details to establish a chain of custody and preserve the contents in the most effective way possible.

When Paper Bags Work Best

However, paper bags are best for other types of evidence, such as blood, saliva, semen, and other body fluid stains. Paper bags work well for both fresh and dried blood or semen stains, for example. Paper evidence collection bags are also useful for storing fabric and textile evidence because air permeability is beneficial with this type of evidence.

Avoid Direct Heat and Cold

With nearly every type of evidence that could be collected at a crime scene, it is important to avoid direct contact with very hot and cold temperatures. Even slight temperature fluctuations can alter a piece of evidence or even destroy it. Also, avoid direct exposure to sunlight to avoid putrefaction and loss.

An Appropriately Sized Container

It’s important to store your evidence in an appropriately sized container to avoid any damage. Evidence bags that aren’t large enough will likely rip and fail over time. While bags that are too big for the sample collected can make the evidence difficult to recover, especially in cases involving gun powder or trace evidence.

Types of Evidence That Need Dry Security Seals

Many forms of evidence require dry security seals, like the ones used in our law enforcement evidence bags. Evidence can be sealed with a heat seal, tape seal, or lock seal. Dry security seals are often crucial when packaging biological evidence, for example. Any leaks in an evidence bag can result in deterioration, contamination, and loss of the sample. Our tamper-proof evidence bags can withstand wear and tear, they’re easy to write on, and they can’t be resealed after opening.

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