Chain of Custody

The term chain of custody refers to the process of maintaining and documenting the handling of evidence. It involves keeping a detailed log showing who collected, handled, transferred, or analyzed evidence during an investigation. The procedure for establishing chain of custody starts with the crime scene. To explore this concept, consider the following chain of custody definition.

Definition of Chain of Custody


  1. A chronological documentation of the handling of evidence throughout a criminal investigation.

What is Chain of Custody?

In considering the chain of custody meaning, it is important to understand that evidence plays a vital role in any criminal investigation. Not only does it help establish the elements of the crime, but it can also identify a victim or perpetrator. When a case goes to trial, a judge and jury rely on evidence to decide a defendant’s guilt or innocence. Common types of evidence include:

  • Blood
  • DNA samples
  • Documents
  • Articles of clothing
  • Photographs
  • Videos
  • Digitally stored data
  • Photographs

When a trial takes place, the prosecution and defense use evidence to prove the facts of the case. If the evidence is not self-authenticating, the proffering party must be prepared to demonstrate its authenticity. In other words, they must be able to show that the item presented is the same item collected from the crime scene.

They also have the burden of proving that the evidence is unaltered and uncontaminated. A primary means of authenticating an item involves analyzing the chain of custody for evidence. This refers to the chronological documentation of who handled it, what they did with it, and where they stored it. In all chain of custody examples, the judge can rule the evidence inadmissible.

Self-authenticating evidence pertains to any item a party can submit without offering additional proof showing its authenticity. Examples of self-authenticating evidence include certified public copies of documents, notarized documents, and newspaper articles.

Procedure to Establish Chain of Custody

The procedure to establish chain of custody begins at the crime scene. A forensics investigator carefully studies the scene and takes photographs and detailed notes for each piece of evidence found. These notes should include:

  • Location of evidence
  • Time and date of evidence recovery
  • Description of item
  • Condition of item
  • Unique markings on items

The investigator then packages and seals the evidence to prevent contamination. Labeling or marking each package accordingly allows for easy identification in the forensics lab or evidence room. Once at the lab, a forensic scientist analyzes the evidence and sends the results to detectives working the case. To maintain an accurate and complete record, these examples of chain of evidence elements must be met:

  • Limit the number of people handling evidence
  • Confirm all names, identification numbers, and dates on the chain of evidence documents
  • Seal the package
  • Double check markings before submission
  • Obtain signed receipts upon transfer

The following is an example of chain of custody involving the recovery of a gun at a murder scene:

  1. An officer on the scene points out a gun to the forensics technician
  2. The technician photographs the gun in place, then picks it up, puts it into a bag, and labels it
  3. The technician transports the gun to the lab for testing, including collecting fingerprints from it
  4. The technician then logs the gun and any other evidence into the evidence room, where a clerk carefully logs it in
  5. The evidence clerk stores the evidence until needed, usually at trial.
  6. Only people with good reason may look at or access the evidence, and a careful log is kept

Chain of Digital Evidence

As technology has advanced, digital evidence has become a more common part of legal proceedings. This includes text messages, social media conversations, photographs, videos, information stored on hard drives, and more.

Just as with physical evidence, law enforcement must maintain a chain of digital evidence. This is especially important as someone could easily erase or manipulate the data. The following example of chain of custody steps can help preserve the reliability and relevancy of evidence.

After law enforcement collects digital evidence, a computer forensics technician analyzes the data before making a copy. The technician may install “a write blocker” or password to reduce the risk of altering the data. Some even use digital hashing to secure the evidence.

The hash uses an algorithm to create a unique impression of the digital content. If anyone alters the data, the algorithm creates a new hash making the tampering apparent. After securing the data, the technician will tag the hardware or device and lock it up. To maintain the chain of digital evidence, anyone that accesses the hardware must log it in and out.

Chain of Drug Test Evidence

A court can order a drug test for various reasons, including child custody disputes and after DUI arrests. Submitting to random drug testing is also a common condition of probation or parole. These tests vary depending on the regulations of each jurisdiction and they detect all types of illegal substances.

The most common tests involve urine or saliva samples, which detect recent drug use. When detecting usage over a long period of time, the court may order a hair follicle test. The results of these court-ordered drug tests can have a real impact on the outcome of the case.

This makes it extremely important to establish a chain of drug test evidence. The process involves documenting every detail regarding the transfer, storage, analysis, and disposal of the sample. Maintaining a chain of drug test evidence reduces the likelihood of accidental or malicious tampering of the sample. It also guarantees that the results belong to the individual that provided the sample.

What Happens if Someone Breaks the Chain of Custody?

In criminal cases, the defendant may petition the court to exclude evidence that the prosecution obtained. This can happen if someone breaks the chain of custody for any reason. If the judge agrees, the prosecution cannot introduce that particular piece of evidence at trial. If the judge suppresses the prosecutor’s main evidence, it can result in dismissal of the case.

A number of factors can break the chain of custody including:

  • Investigators waiting too long to collect evidence
  • Improper storage of evidence
  • Mislabeled evidence
  • Alteration of digital evidence
  • Unauthorized person accesses evidence

Motion to Suppress Evidence

Generally, the discovery process is where a motion to suppress evidence may happen if someone breaks the chain of custody. This process takes place before the trial and involves the prosecution and defense exchanging evidence. Discovery allows both parties to adequately prepare for trial. In all chain of custody examples, the judge ultimately determines what evidence to allow.

Chain of Custody Example Sale of Marijuana

In 2012, police executed a search of Stephen Conlin’s residence. During the search, officers found marijuana, evidence of a marijuana-grow operation, and several drugs. Police seized 14 bags containing marijuana and charged Conlin with third degree sale of marijuana while in possession of a firearm.

Conlin petitioned the court to suppress evidence, claiming law enforcement did not have probable cause to obtain the search warrant. The court denied his motion, and the jury found him guilty on both counts. He was sentenced to probation. Conlin appealed his conviction claiming the state did not present evidence that the marijuana weighed at least 5 kilograms.

After reviewing the case, the high court remanded it to the district court for a conviction of 5th-degree possession. This decision was based on law enforcement’s failure to maintain an adequate chain of custody.

Days after Conlin’s arrest, an officer not involved in the investigation took 20 bags of marijuana from the evidence room. He used the evidence in a dog-sniff training exercise, but he did not sign the evidence out on a chain-of-custody log sheet.

He also testified that he did not return the bags to the evidence room until the next day. The court excluded 12 of the bags. The remaining two weighed under 5 pounds, the minimum needed for a conviction of third-degree sale of marijuana

In this chain of custody example, the court’s exclusion of evidence led to a reduction in the defendant’s charges.

Related Legal Terms and Issues

  • Acquit – To relieve someone from a criminal charge; to declare not guilty.
  • Defendant – A party who is the target of a lawsuit in civil court, or who stands accused of, or charged with, a crime or offense.
  • Evidence – Information presented to a court or jury in proof of the facts, including testimony of witnesses, records, documents, or objects.
  • Hearing – A proceeding in which the court hears an issue of fact or law by hearing evidence and testimony presented, and then makes a decision.
  • Jurisdiction – The legal authority to hear legal cases and make judgments; the geographical region of authority to enforce justice.
  • Jury – A group of people sworn to render a verdict in a trial, based on evidence presented.
  • Prosecution – The lawyer or lawyers who charge and try a case against a person accused of committing a crime.
  • Victim – A person who is injured, killed, or otherwise harmed as a result of a criminal act, accident, or other event.