CHFI Computer Forensics Fundamentals and Process Practice Question
Which principle states that every contact leaves a trace?
⚠ Common exam trap
EC-Council often tests the distinction between a forensic principle (Locard's) and legal or procedural rules (chain of custody, best evidence, hearsay), so candidates mistakenly select a legal term that sounds related to evidence handling rather than the core scientific concept.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
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Locard's exchange principle
Locard's exchange principle is the foundational forensic concept stating that whenever two objects come into contact, there is a transfer of material between them. In computer forensics, this means that digital activity—such as accessing a file, sending a packet, or connecting to a network—inevitably leaves traces in logs, memory, registry entries, or file metadata. This principle underpins the entire discipline of digital evidence recovery.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Locard's exchange principle
Why this is correct
Locard's exchange principle, articulated by French forensic scientist Edmond Locard, holds that every contact between a person and an environment results in a mutual transfer of material. This foundational axiom means a perpetrator both leaves trace evidence at a scene and carries trace evidence away, enabling forensic examiners to link individuals to locations. It is the scientific basis for analyzing fibers, hair, glass, soil, biological fluids, and even digital residues.
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Chain of custody
Why it's wrong here
Chain of custody is a procedural and legal framework that documents every seizure, transfer, possession, and disposition of evidence from collection to court presentation. It establishes the authenticity, integrity, and admissibility of evidence by maintaining a chronological record of each custodian, often requiring signatures and secure storage logs. A break in the chain can result in exclusion, but the concept addresses evidence handling and accountability, not the physical phenomenon of contact transfer.
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Best evidence rule
Why it's wrong here
The best evidence rule, codified in rules such as Federal Rule of Evidence 1002, requires that the original writing, recording, or photograph be produced to prove its content, unless an exception applies. It prioritizes originals over copies to prevent errors or misrepresentation inherent in secondary sources. This rule concerns the reliability of documentary proof, not the exchange of trace material between objects, and therefore has no bearing on the principle that every contact leaves a trace.
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Hearsay rule
Why it's wrong here
The hearsay rule is an evidentiary prohibition against admitting out-of-court statements offered to prove the truth of the matter asserted, because such statements lack the safeguards of cross-examination, oath, and demeanor observation. Numerous exceptions exist when the statement carries circumstantial guarantees of trustworthiness, but the rule fundamentally governs testimonial evidence about what someone said. It does not describe physical interactions, transfer of material, or any forensic principle about trace deposition.
Go deeper
Related to this question
Learn chapter
Overview of Computer Forensics and Investigation Process
Key term
Memory Acquisition
Memory acquisition is the process of capturing the contents of a computer's volatile memory to preserve data for forensic analysis and incident response.
Key term
Forensic Evidence Collection
Forensic evidence collection is the process of identifying, preserving, and gathering digital data from computers and devices in a way that keeps it valid for use in legal investigations or internal incident response.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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