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Evidence Storage Systems for Law Enforcement

A complete guide to designing a secure, defensible evidence room — pass-through intake lockers, refrigerated and biological storage, weapons and narcotics security, high-density shelving, and chain-of-custody tracking. Designed, supplied, and installed by Material Handling USA.

Evidence storage room with closed-back steel shelving and lockable mesh doors holding sealed evidence bags and numbered boxes

72 hrs

NIST dividing line between short-term and long-term evidence storage

2–8 °C

Refrigerated storage range defined for biological evidence

30+ yrs

Designing and installing storage systems for public-safety agencies

Free

Space planning, layout drawings, and quotes

Build an Evidence Room You Can Defend in Court

An evidence room has two jobs: keep every item intact, and prove who touched it. Everything else — shelving type, locker configuration, refrigeration, aisle layout — exists to serve those two jobs. This guide walks through the workflow an evidence room has to support, the storage equipment that fits each stage, and the planning decisions that are expensive to change later.

Material Handling USA designs, supplies, and installs evidence storage for police departments, sheriff’s offices, crime labs, courts, and campus public-safety agencies. We work from your intake volumes, retention rules, and floor plan — not from a catalog page. Questions on your project? Call (800) 326-4403 or request a free design consultation.

Intake & Chain of CustodyPass-Through LockersShort vs. Long-TermRefrigerated & BiologicalWeapons, Narcotics & OversizedHigh-Density ShelvingCages & Restricted AccessLabeling & TrackingRoom PlanningInstallation ProcessFAQs

Evidence Intake and Chain of Custody

Chain of custody starts the moment an item leaves an officer’s hands. The weak point in most evidence rooms is not the shelving — it is the gap between an after-hours seizure and the technician who logs it the next morning. A designed intake area closes that gap.

A workable intake sequence looks like this:

  • Package and seal at the scene or at a processing bench, with case number, item number, date, and collecting officer on the label.
  • Deposit into a temporary locker that locks on close, so no second person is needed at 3 a.m.
  • Log and barcode when the custodian retrieves the item, creating the first documented transfer.
  • Assign a permanent location — shelf, bin, refrigerator, weapons rack, or bulk bay — recorded against the item record.
  • Record every later movement: lab submission, court check-out, return, disposition.
Evidence intake area with numbered pass-through property lockers and a service window
Evidence intake counter with numbered pass-through property lockers

The workflow your storage has to support

Diagram of the evidence storage workflow: intake and logging, segregation, secure transfer, then audit and release
Evidence storage workflow: intake and logging, segregation, secure transfer, audit and release

Design principle

Every hand-off is a place evidence can be challenged. Reduce hand-offs with pass-through lockers and single-purpose storage zones, then document the hand-offs you cannot remove.

Pass-Through and Temporary Evidence Lockers

Temporary lockers hold evidence between deposit and processing. They come in two configurations, and most agencies end up using both.

Pass-through lockers are built into the wall separating the drop-off area from the secure property room. The officer loads from the public/patrol side; the custodian unloads from inside the secure room through a rear door. Nobody without evidence-room access ever stands in the evidence room.

Non-pass-through lockers are accessed from one side only. They cost less and can go anywhere there is wall space — satellite stations, garages, precinct hallways, or areas where a shared wall with the evidence room does not exist.

Both types use one-way keyless latches: the compartment locks when the door closes, and only the custodian can reopen it. Compartment sizes are mixed within one bank so a phone, a rifle, and a bag of clothing all have a home. Refrigerated inserts and drying compartments can be built into the same bank.

Dasco pass-through evidence locker with rear swing gate access
Pass-through evidence locker with the rear access door open, showing individual locking compartments
Pass-through lockers Non-pass-through lockers
Access Loaded from outside, emptied from inside the secure room Loaded and emptied from the same side
Installed Recessed into the wall between drop-off and evidence room Surface-mounted against any wall
Best for Main station intake, 24/7 deposits, highest chain-of-custody separation Satellite offices, remodels, limited wall space, overflow
Locking One-way keyless latch on deposit; rear master access One-way keyless latch on deposit; front master access
Options Refrigerated inserts, drying compartments, mixed compartment sizes, electronic locks Same option set, single-side service
Trade-off Requires a shared wall and coordination with the building Custodian must enter the deposit area to retrieve

Configuration behavior described above reflects published manufacturer documentation for pass-through and non-pass-through temporary evidence lockers.

Electronic evidence locker bank with keypad access for a police departmentElectronic & Smart LockersKeypad or credential access with an audit log per compartment. Useful where the agency wants electronic records of every deposit and retrieval.
Stainless steel refrigerated evidence locker with individually locked compartmentsRefrigerated Locker InsertsRefrigerated compartments inside a temporary locker bank so biological evidence goes straight into cold storage at deposit.
Stainless steel forensic evidence drying cabinet with glass doorDrying Cabinets at IntakeWet and bloody items are dried in a filtered cabinet before packaging, one case per cabinet, to prevent cross-contamination.

Temporary, Short-Term, and Long-Term Storage

The 72-hour mark is the useful dividing line. The NIST Technical Working Group on Biological Evidence Preservation recommends treating any location that holds evidence for up to 72 hours as short-term storage, and any location holding evidence longer than 72 hours as long-term storage. That single distinction drives most equipment decisions.

Short-term storage is about speed and separation: temporary lockers, a drying cabinet, a refrigerator near the intake bench, and a bench with power and a scanner. Capacity is measured in items per shift.

Long-term storage is about density, retrieval, and years of growth. Serious-crime evidence may be retained for decades, so long-term areas are where high-density mobile shelving, cantilever bays for bulk items, and locked cages earn their keep. Capacity is measured in linear feet per square foot of floor.

Retention periods themselves are set by state law, court rules, and your agency policy — they vary by jurisdiction and case type. Build the room around your own retention schedule rather than a national rule of thumb.

Long-term evidence storage room with labeled boxes on closed-back high-density shelving
Long-term evidence storage room with labeled boxes on high-density shelving

Storage condition definitions used in forensic practice

Condition Definition Typical equipment
Frozen Maintained thermostatically at or below −10 °C (14 °F) Forensic freezer, alarmed and logged
Refrigerated Maintained thermostatically between 2 °C and 8 °C (36–46 °F) at less than 25% humidity Evidence refrigerator or refrigerated locker insert
Temperature controlled Maintained thermostatically between 15.5 °C and 24 °C (60–75 °F) at less than 60% humidity Conditioned evidence room with shelving or mobile shelving
Room temperature Ambient temperature of the surroundings; may have no temperature or humidity control Unconditioned bulk or overflow storage

Definitions: NIST IR 7928, The Biological Evidence Preservation Handbook and its companion storage-conditions summary. Confirm the storage condition required for a specific item type with your crime laboratory.

Refrigerated and Biological Evidence Storage

Refrigerated cabinet and closed-back shelving holding biological evidence kit boxes in a secure storage room
Refrigerated cabinet and closed-back shelving holding sealed biological evidence packaging

Biological evidence fails quietly. Moisture, heat, and condensation degrade DNA long before anyone notices, so the equipment around biological evidence matters as much as the shelving.

  • Dry before packaging. Wet or bloody items are air-dried in a drying cabinet or dedicated drying room, one case at a time.
  • Use breathable packaging for dried biological items — sealed plastic traps moisture and encourages bacterial growth.
  • Refrigerate what cannot be dried yet in a nonporous container at 2–8 °C, away from direct sunlight, until it can be dried or submitted.
  • Freeze what the lab specifies — some sample and extract types are stored frozen; confirm requirements with your laboratory.
  • Log temperature on every refrigerator and freezer, and alarm the ones holding irreplaceable samples.
  • Separate cases physically with closed-back shelving, bins, or dividers so packaging never touches packaging from another case.

Equipment that belongs in this zone: forensic refrigerators and freezers with lockable doors and temperature logging, refrigerated locker inserts at intake, filtered drying cabinets, closed-back steel shelving for sexual assault kits and boxed biological evidence, and stainless work surfaces that can be decontaminated.

Personal protective equipment, biohazard spill supplies, and an eyewash or safety shower belong in the same area — the International Association for Property and Evidence lists all of these in its published property-room safety standards. Fire, life-safety, and building requirements are set by your local and state authorities, so verify them with your fire marshal and building department during design.

A man in a lab coat examines a drying cabinet in the law enforcement department, revealing a green shirt with visible stains. Inside are also jeans and shoes. The scene suggests a meticulous investigation process amidst a scientific environment.
Evidence technician loading clothing into a forensic drying cabinet in a law enforcement facility

Weapons, Narcotics, and Oversized Evidence

Some categories need their own room, rack, or vault. Mixing them into general shelving creates safety problems, audit problems, and — with narcotics — regulatory exposure.

Open weapon rack holding rifles and long guns for law enforcement evidence storageFirearms and Long GunsBarrel-supported racks and weapon cabinets keep firearms separated, visible for audit, and off general shelving. Ammunition is stored separately. Cabinets and racks can be locked inside a larger restricted area for two-layer control.
Narcotics evidence vault interior with heavy steel door, camera and evidence shelvingNarcotics and Controlled SubstancesA vault, modular strongroom, or locked cage with restricted keying, camera coverage, and its own access log. Handling and destruction rules come from state and federal authorities — design the space around the rules your agency operates under.
Cantilever racking holding recovered bicycles and long bulk evidence itemsOversized and Bulk ItemsBicycles, ladders, tires, doors, and recovered property need cantilever racking or wide-span bays, plus a door and aisle path wide enough to actually move them. Plan the route before the rack.
Digital forensics locker bank above a technician work surfaceDigital Devices and MediaPhones, drives, and cards are stored in individual compartments with faraday or shielded pouches when required, near a forensics bench with power and network access, and away from magnets and heat.

High-Density Shelving: Getting More Room Without a Bigger Room

Static shelving spends most of your floor on aisles. High-density mobile shelving puts shelving carriages on floor rails so they share a single moving aisle — the same footprint holds substantially more evidence, and an addition or off-site warehouse can often be avoided.

Three drive types cover nearly every evidence room:

  • Manual / direct-pull — light carriages moved by hand. Lowest cost, best for smaller rooms and low-frequency retrieval.
  • Mechanical assist — a three-spoke handle and gear drive moves heavy loaded carriages with modest effort. The most common choice in evidence rooms.
  • Powered / electric — push-button movement with safety sweeps and optional keypad or card lock-down of individual aisles.

Carriages are configured with closed-back shelving, bins, dividers, weapon shelves, and lockable mesh or solid doors, so one system can hold boxed evidence, bagged evidence, and secured categories side by side.

Aurora mobile shelving system at Roy Police Department evidence room Utah
High-density mobile shelving carriages with an open aisle and floor rail in a police evidence room
Static shelving Mobile (mechanical assist) Electric mobile
Aisles One fixed aisle per shelving row One shared moving aisle One shared moving aisle
Capacity in the same footprint Baseline Substantially higher Substantially higher
Retrieval effort Immediate access to every row Turn a handle to open the aisle Press a button to open the aisle
Aisle-level security Add doors or cages Lockable carriage doors and aisle locks Keypad or credential lock-down by aisle
Floor requirements Level floor Rail track, leveled and grouted as needed Rail track plus power
Best fit Small rooms, very high pick frequency Most evidence rooms, long-term retention High-volume rooms, ADA and audit-driven access control

Real project

The Weslaco Police Department (TX) evidence room was losing floor space to fixed aisles. Material Handling USA designed and installed a mechanical-assist mobile shelving system with double-entry carriages on rail track, using 48" wide by 24" deep shelving sections sized for evidence boxes and bags — read the case study.

Secure Cages, Vaults, and Restricted Access

Modular evidence vault interior with rated door, evidence shelving and a chain-of-custody intake counter
Modular evidence vault interior with rated door, evidence shelving and work counter

Not every item needs the same level of protection. Layered security lets you spend control where it matters: the evidence room is restricted, and rooms-within-the-room hold the categories that need a second lock and a separate log.

Wire mesh cages build a lockable enclosure inside an existing room — high-value property, narcotics, firearms, or a single case that needs isolation. Mesh keeps the space visible for camera coverage and lets sprinklers and airflow through.

Modular strongrooms and vaults add hardened walls and a rated door where an agency wants a genuine vault without pouring concrete.

Access control ties it together: restricted keying or credentials, door-status monitoring on evidence-room doors, motion detection inside storage spaces, camera coverage at intake and at every secured enclosure, and duress alarms where staff work alone. Federal facility-planning guidance for forensic facilities recommends exactly this combination of monitored doors, motion detection in evidence spaces, and duress alarms in key areas.

Security-design guidance summarized from the U.S. Department of Justice / NIJ Forensic Laboratories: Handbook for Facility Planning, Design, Construction, and Moving.

Labeling, Tracking, and Retrieval

Storage is only as good as your ability to find an item and prove its history. A location scheme plus barcodes turns a room full of bags into a searchable inventory.

  • Label the room, not just the items. Every range, carriage, shelf, and bin gets a permanent, human-readable location code.
  • Barcode at first logging and scan on every transfer — intake, lab, court, return, disposition.
  • Store by location, not by case. Sequential shelf assignment fills the room evenly; the record, not the shelf, keeps cases together.
  • Give purge candidates their own zone so disposition reviews do not require walking the whole room.
  • Audit against the record — random shelf-to-record and record-to-shelf checks catch drift early.

Barcode scanning is the practical baseline. RFID adds bulk reads and near-real-time location visibility; a NIST assessment of RFID in forensic evidence management catalogs those benefits alongside the cost and implementation barriers, which is the trade-off to weigh before committing.

Technician scanning a barcode on a sealed evidence bag at an evidence room intake counter
Technician scanning a barcode on a sealed evidence bag at an evidence intake workstation

Reference: NIST IR 8030, RFID Technology in Forensic Evidence Management.

Evidence Room Planning and Layout

Layout is decided by flow. Evidence should move in one direction — from intake, through processing, into storage, and out through release or destruction — without crossing back through unsecured space.

A workable zoning pattern:

  • Deposit zone (outside the secure room): temporary lockers, drop counter, camera.
  • Processing zone: bench, scanner and printer, packaging supplies, drying cabinet, refrigerator.
  • General long-term storage: high-density mobile shelving on rail, sized for your box and bag mix.
  • Restricted zones: narcotics vault or cage, weapons racks, high-value cage.
  • Cold storage: refrigerators and freezers with logging, on conditioned power.
  • Bulk and oversized: cantilever or wide-span bays with a clear path to a wide door.
  • Release and disposition: staging area for court check-out, return to owner, and destruction.

Get the dull numbers on paper first: annual intake, current linear feet in use, growth rate, retention schedule, ceiling height, clear door widths, floor levelness and slab capacity, sprinkler and lighting positions, HVAC capability, and where power and data can land.

Layout drawing for mobile shelving at Roy Police Department
Mobile shelving layout drawing for a police department evidence room, showing carriages, rail and aisle

Evidence room planning checklist

  • Annual intake volume and five-year growth estimate documented
  • Retention schedule confirmed with your agency counsel or court rules
  • Current inventory measured in linear feet, by package type
  • Special categories counted: firearms, narcotics, biological, digital, oversized
  • Cold-storage capacity needed, with logging and alarm requirements
  • Ceiling height, sprinkler and light positions verified against shelving height
  • Floor levelness and slab capacity checked for rail-mounted systems
  • Door and corridor widths measured for oversized items and for installation
  • Access control, camera coverage, and door monitoring scoped with your IT or security vendor
  • Safety equipment planned: PPE, spill kit, eyewash, ventilation, duress alarm
  • Fire and building requirements confirmed with your local fire marshal and building department
  • Installation window, after-hours access, and evidence relocation plan agreed

Free space plan

Send us your room dimensions and inventory counts and we will return a layout drawing with capacity options — the same deliverable used on the Roy and Weslaco police department projects. Request a free evidence room design or call (800) 326-4403.

Installation and Project Process

Evidence rooms cannot go offline, so the sequence matters as much as the equipment. Our projects follow the same five steps.

1

Consultation

We review intake volume, retention rules, special categories, and the constraints of the space — in person or by video.

2

Site measure

Floor, ceiling, doors, sprinklers, power, and slab conditions are verified before anything is drawn.

3

Layout and quote

You receive layout drawings with capacity options and a line-item quote, including accessories and installation.

4

Delivery and install

Factory-trained crews install rail, carriages, shelving, lockers, and cages — scheduled around your operations, including after hours.

5

Move-in and support

We help sequence the relocation of existing evidence, then provide operating training, warranty support, and future add-on carriages.

Recent public-safety projects

Aurora mobile shelving carriages installed in the Weslaco Police Department evidence roomWeslaco Police Department, TXMechanical-assist mobile shelving with double-entry carriages on rail track, configured for evidence boxes and bags.
Mobile shelving carriages installed at Roy Police Department in UtahRoy Police Department, UTHigh-density mobile shelving designed from a room layout drawing to expand evidence capacity inside the existing footprint.
Front view of mobile shelving carriages with three-spoke handles at Weslaco Police DepartmentMechanical-Assist HandlesThree-spoke handle drives let one technician move fully loaded carriages, which is what makes high-density practical for daily evidence retrieval.

Frequently Asked Questions About Evidence Storage

What is the difference between a pass-through and a non-pass-through evidence locker?
A pass-through locker is built into the wall between the drop-off area and the secure evidence room, so an officer deposits from one side and the custodian retrieves from inside the secure room. A non-pass-through locker is accessed from a single side. Pass-through units give the cleanest separation; non-pass-through units are easier to add to an existing building.
How long is “short-term” evidence storage?
The NIST Technical Working Group on Biological Evidence Preservation recommends treating storage of up to 72 hours as short-term and anything longer than 72 hours as long-term. Actual retention periods are set by state law, court rules, and agency policy.
What temperature is used for refrigerated and frozen evidence?
In published forensic guidance, refrigerated storage means a thermostatically maintained 2–8 °C (36–46 °F) at under 25% humidity, and frozen means at or below −10 °C (14 °F). Temperature-controlled rooms are 15.5–24 °C (60–75 °F) at under 60% humidity. Confirm the requirement for a specific item type with your crime laboratory.
Can biological evidence be stored in sealed plastic?
Dried biological evidence is generally stored in breathable packaging, because sealed non-breathable packaging traps moisture and encourages bacterial growth that degrades DNA. Items that cannot be dried yet are placed in a nonporous container and refrigerated until they can be dried or submitted.
Can mobile shelving be retrofitted into an existing evidence room?
Yes — mobile shelving is regularly installed in existing rooms. Rail is mounted to the floor and leveled, so the practical questions are slab condition, ceiling and sprinkler height, door width for installation, and how the existing evidence will be relocated in stages. We confirm all of that at site measure before quoting.
How much space does high-density shelving save?
It depends on your current aisle count, shelving depth, and ceiling height, because the savings come from eliminating fixed aisles. Rather than quote a generic percentage, we measure your room and return a layout drawing showing your actual capacity with static shelving versus mobile carriages.
Does a storage system make our agency compliant or accredited?
No. Accreditation programs such as IAPE’s property-room accreditation review policies, procedures, training, documentation, and facilities as a whole — equipment alone does not confer compliance or accreditation. Well-designed storage supports the facility and documentation portions of a review; the rest is agency practice.
How do you keep chain of custody intact with high-density mobile shelving?
Chain of custody lives in the record, not the shelf. Each carriage, shelf, and bin gets a permanent location code, items are barcoded at logging and scanned on every transfer, and aisles can be locked individually with carriage doors or electronic aisle lock-down on powered systems.
What does an evidence storage project cost?
It varies with room size, drive type, security level, and accessories, so we quote from a measured layout instead of a price list. Space planning, layout drawings, and quotes are free — call (800) 326-4403 or request a quote.
Do you handle installation and moving the existing evidence?
Yes. Factory-trained crews handle installation, and we help sequence the relocation of existing evidence so the room keeps operating. Work can be scheduled after hours or in phases where evidence-room access is restricted.

Need Help Designing Your Evidence Room?

Speak with a specialist who can design the right solution for your space, your retention rules, and your budget. Free space planning, layout drawings, and quotes.

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