Throughout my career in law enforcement, I’ve tested some pretty interesting tools designed to aid officers and detectives in the field. While many products promise innovation, few deliver solutions that address the nuanced challenges of policing. But the Mission Darkness Charge Preserve Evidence Bag from MOS Equipment is one of those products that work.
In modern law enforcement, collecting electronic evidence while preserving DNA integrity presents a major challenge. Smartphones, tablets and other devices often contain critical digital evidence, but they also hold fingerprints, touch DNA and other biological traces that can be lost if mishandled. When electronic evidence is placed directly into a reusable Faraday bag, this automatically opens that piece of evidence for scrutiny because of cross-contamination from previous devices placed in that bag. To reduce these claims, detectives place the device into an evidence bag first, then put the evidence bag into a reusable Faraday bag. The evidence bag protects the devices from cross-contamination, but then investigators can’t access or charge the device without opening the evidence bag first.
The Mission Darkness Charge Preserve Evidence Bag (available at MOS Equipment) solves this problem by allowing devices to stay powered while sealed in a secure, contamination-proof bag. It’s the first of its kind to integrate charging capabilities directly into the evidence bag.
| RELATED: Shielding your tech: Why every police officer needs a Faraday bag
The dual challenge: Power vs. preservation
When officers seize a device, they face two conflicting priorities:
- Keeping the device powered: Modern smartphones often employ encryption that locks data permanently if the battery dies or the device is powered off. Without a live device, forensic extraction becomes impossible without the suspect’s passcode.
- Preserving DNA and avoiding contamination: Traditional evidence bags require devices to be powered off, risking data loss. Meanwhile, placing a contaminated device (blood, drugs, or other residues) into a Faraday bag can render the bag unusable for future cases.
The Charge Preserve Evidence Bag eliminates these issues by enabling continuous charging inside a sealed, protective evidence bag. The evidence bag includes a built-in conductive charging port, allowing a USB-C, USB micro, and USB Lightning connections without breaking the seal. All cables are lab tested and UL-certified, so you can rest assured that the cables will work when deployed.
Not just an evidence bag: Works alongside Faraday bags
For cases requiring signal isolation, the Charge Preserve Bag can be placed inside a Faraday bag while still allowing charging. It pairs seamlessly with the Mission Darkness Charge & Shield Faraday Bag for long-term power delivery, but is also compatible with other Faraday bags and charger setups for short-term charging needs.
For me, one of the top features of these bags is that you do not have to worry about damaging your more expensive Faraday bag. The last thing I want to do is stick a contaminated phone inside a Faraday bag, destroying that bag in the process. The Charge Preserve Bag is a cost-effective option to protect your more expensive equipment.
Preserving chain of custody: Detailed evidence fields printed directly on the bag
During defense workshops, I have seen how gaps in documentation undermine cases. One of the easiest and fastest ways to derail a prosecution is to focus on chain-of-custody issues. This method of attack is particularly easy when it comes to electronic evidence. Many police agencies temporarily store electronic evidence outside of their department’s evidence section, especially when the device is being processed or extracted. Furthermore, the phone has to be removed from the evidence bag during the extraction process, which can open that item to scrutiny in court.
The Charge Preserve Evidence Bag has pre-printed fillable fields for all the required chain-of-custody information. The officer or detective on scene can place the device directly into the evidence bag, seal it using the tamper-evident seals, and complete all the required fields before even setting foot in the department’s evidence section. This removes all the potential chain-of-custody allegations. When the detective goes to extract the device, he can leave the device sealed in the evidence bag. And since the device is sealed from outside elements, defense attorneys will not be able to raise the concern of cross-contamination with other devices previously placed in the same Faraday bag.
Another benefit is that since each device is already sealed in its own evidence bag, detectives can place multiple devices into the same Faraday equipment. This is where I prefer using Faraday duffle bags like the Mission Darkness Disconnect Faraday Duffel Bag or the Mission Darkness Odin Guard Faraday Backpack.
How it works: Step by step
The Charge Preserve Evidence Bag is very easy to use.
Insert the device: Place the device into the correct Charge Preserve Bag. There are three bags to choose from (USB-C, USB micro, USB Lightning).
Connect the cable: Attach the integrated USB tip to the device’s port.
Seal the bag: Use the tamper-evident closure. Sign and date the seal per your agency’s instructions.
Power up: Plug the external cable into a power bank, wall outlet, or forensic tool.
Document on-site: Fill the pre-printed fields (case number, officer ID, Timestamps) immediately to eliminate gaps in the chain of custody.
(Optional) RF shielding: For signal-sensitive cases, place the Charge Preserve Evidence Bag inside a Mission Darkness Faraday Bag or Faraday bag of your choice.
Conclusion
Before using this bag and attending defense workshops on chain of custody, I severely underestimated the risks of traditional electronic evidence collection. I didn’t realize the critical gap in our evidence process — balancing charging power needs with biological preservation seemed impossible. The Charge Preserve Evidence Bag isn’t just another gadget — it’s a paradigm shift in how we handle electronic evidence.
For agencies looking to enhance their evidence collection process, eliminate defense claims of cross-contamination, or if you just want to protect your current Faraday bags, the Charge Preserve Evidence Bags are for you.
Learn more or purchase the MOS Equipment Charge Preserve Evidence Bag here.
