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newSchoolWorks.com › VoTechWorks › Agriculture, Environment & Public Service › Crime Scene / Forensic Technician › Lab Practicum: Forensic Evidence Processing and Analysis › Lesson 2
AGR-CSI53-08 · Lesson 2 · 10 clock hours · theory

Evidence Intake, Packaging Standards, and Chain of Custody in the Lab

Objective. Students will receive simulated evidence submissions, verify packaging integrity, complete laboratory intake forms, and enter items into a manual evidence log without chain-of-custody breaks.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed professional in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

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Why Evidence Intake and Chain of Custody Matter

Every piece of physical evidence that enters a forensic laboratory carries a legal history. From the moment an item is collected at a scene to the moment it is presented in court, every person who touches it, moves it, or examines it must be documented. This unbroken record is called the chain of custody. A single undocumented transfer—even an innocent one—can allow a defense attorney to argue that evidence was tampered with or substituted, potentially destroying a prosecution. In the lab, that responsibility begins the instant you sign for an incoming item.

The Intake Process: Step by Step

Receiving the submission. When a submitting officer or investigator brings evidence to the lab, your first task is to verify the submission paperwork before you touch any packaging. Confirm that the submitting agency, case number, and item list on the submission form match what is physically present. Do not sign for items you have not counted and visually inspected.

Inspecting packaging integrity. ASTM E1492 is the standard practice for receiving, documenting, and storing forensic evidence. It requires that packaging be intact, properly sealed, and clearly labeled before the lab accepts it. Check every seal. Look for torn tape, resealed openings, punctures, leaks (especially on biological or chemical evidence), and missing or illegible item numbers. Any defect you find must be recorded on a nonconformance form before you make an accept-or-reject decision. If you accept a defective package, document every defect in writing and notify a supervisor. If you reject it, the submitting party must re-package appropriately before resubmission.

Completing intake forms. Once you accept an item, you assign it a unique laboratory accession number. This number stays with the item for its entire life in the lab. Write it clearly on the lab's intake form and on the evidence seal you apply. Fill in the item description (using objective, factual language—describe what you see, not what you assume it is), the date and time of receipt, and your printed name and signature. Never leave a field blank; write "N/A" if a field genuinely does not apply.

Entering items into the evidence log. The manual evidence log (or its electronic equivalent) is the lab's master record. Each entry must include the accession number, case number, item description, location where the item will be stored (locker number, freezer bay, etc.), and the name of the person placing it in storage. If a barcode scanner is available, scan the item and verify that the system record matches your handwritten forms before you close out the entry.

Chain-of-Custody Forms

A chain-of-custody (COC) form travels with the evidence. Every transfer—from submitting officer to intake technician, from intake technician to analyst, from analyst to secure storage—requires two signatures: the person releasing the item and the person receiving it, with the date, time, and reason for the transfer recorded. There should be zero gaps in this record. If an item was moved and no one signed for it, that is a chain-of-custody break, and it must be reported immediately through your lab's established protocol.

Key rules for COC documentation:

Accession Numbering

Most laboratories use a structured accession number that encodes the year, a sequential case identifier, and an item number within that case—for example, a format such as 2025-04817-003 might mean the third item in case 04817 received in 2025. Whatever format your lab uses, apply it consistently. Accession numbers must be unique; duplicating a number corrupts the log and can mingle two cases' records.

Storage and Location Tracking

After intake, each item goes to an assigned storage location appropriate to its type: ambient evidence lockers for dry items, refrigerators for perishable biological samples, freezers for items requiring very low temperatures, and separate locked areas for narcotics or firearms (per your lab's security protocols). Log the exact location in your evidence management system at the time of storage. If an item is later moved—say, from the locker to an analyst's bench—that transfer must be documented before the move occurs, not after.

Safety Considerations

Always treat incoming biological evidence as potentially infectious. Wear nitrile gloves, and add a face shield and gown when handling items suspected to contain bloodborne pathogens. Do not eat, drink, or touch your face in the evidence-handling area. When opening packages that may contain sharp objects (knives, broken glass, needles), cut away from your body and inspect contents visually before reaching in. Chemical or narcotics evidence may require a respirator; follow your lab's standard operating procedure and OSHA guidelines for hazardous materials. Dispose of used gloves and packaging materials in the designated waste containers before leaving the intake area.

Key terms8

Chain of custodyThe continuous, documented record of every person who possessed or transferred a piece of evidence, from collection through court presentation, with no gaps or unaccounted transfers.
Accession numberA unique identifier assigned by the laboratory to an evidence item at intake; it links all lab records, paperwork, and storage locations for that item throughout its time in the lab.
ASTM E1492The ASTM International standard practice that establishes requirements for receiving, documenting, and storing physical and biological evidence in a forensic laboratory setting.
Nonconformance formA laboratory document used to record observed defects in incoming evidence packaging, such as broken seals or missing item numbers, and to document the accept-or-reject decision.
Packaging integrityThe condition of evidence packaging being intact, properly sealed, and correctly labeled so that its contents have not been altered, contaminated, or accessed since it was packaged at the scene.
Transfer receiptThe portion of a chain-of-custody form documenting a single transfer of evidence, including the releasing party's signature, the receiving party's signature, and the date, time, and reason for transfer.
Evidence logThe master record—manual or electronic—maintained by the laboratory listing every evidence item in its possession, with accession numbers, case numbers, descriptions, and current storage locations.
Tamper-evident sealA label or tape applied over a package closure that is visibly damaged or leaves a void pattern if the package is opened, providing a physical indicator that the seal has been breached.
In class: Intake drill: instructor provides 10 pre-packaged simulated evidence items with intentional packaging defects (torn seal, missing item number); students inspect each item, document defects on a nonconformance form, and decide whether to accept or reject each. · Lecture and demonstration: instructor walks through a real-world laboratory evidence management system workflow using a projected screen, showing accession numbering, location tracking, and transfer receipt requirements. · Practice round: each student individually receives, accessions, and stores five simulated items, completing all required paperwork; a peer checks the completed chain-of-custody forms against a rubric.
Materials: Pre-packaged simulated evidence items, laboratory intake forms, chain-of-custody forms, evidence seals and tamper-evident tape, permanent markers, barcode scanner (if available), evidence storage lockers, ASTM E1492 packaging standard reference
Check: Student's intake paperwork for all five items is error-free on accession number, item description, date/time, and transfer signatures; zero unaccounted transfers; graded pass/fail by instructor using a 10-point rubric with a minimum of 9/10 correct fields.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Evidence handling and chain of custody
1. A submitting officer brings in a sealed evidence bag. You notice the heat seal at the top is partially open and there is no item number on the label. What is the correct first action?
Evidence handling and chain of custody
2. Which document must accompany a piece of evidence every time it is moved from one person or location to another inside the laboratory?
Documentation and record keeping
3. A technician accidentally writes the wrong date on a chain-of-custody form. What is the correct way to fix this error?
Evidence handling and chain of custody
4. You are logging an incoming item and the accession number you were about to assign already exists in the evidence log for a different case. What should you do?
Evidence packaging and standards
5. According to ASTM E1492, which of the following is a required element when labeling an evidence package for laboratory intake?
Laboratory safety and PPE
6. Incoming biological evidence shows visible moisture inside the packaging. Which PPE should you don before opening the package?
Evidence handling and chain of custody
7. After placing an evidence item in a storage locker, you realize you forgot to log the locker number in the evidence management system. Why is this a serious problem?
Documentation and record keeping
8. During a peer review of your completed intake paperwork, your classmate finds that you left the 'time of receipt' field blank on one of five chain-of-custody forms. Under the lesson's pass/fail rubric, what is the likely outcome?
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