The correct answer is Locard's exchange principle because it establishes that every contact leaves a trace, meaning the suspect's interaction with the computer—such as typing, accessing files, or connecting peripherals—will inevitably create unique digital artifacts like registry keys, prefetch files, or USB serial numbers. In digital forensics, this principle directly refutes a claim of evidence planting by demonstrating that those artifacts could only have been generated by the suspect's specific actions or device, not by an external party. On the Computer Hacking Forensic Investigator CHFI exam, this concept tests your understanding of how physical-world forensic logic applies to digital evidence, often appearing in scenario-based questions where a suspect denies involvement. A common trap is confusing this with chain of custody, but remember: Locard is about trace transfer, not documentation. Memory tip: "Every contact leaves a trace—even a digital touch leaves a trace."
CHFI Computer Forensics Fundamentals and Process Practice Question
This CHFI practice question tests your understanding of computer forensics fundamentals and process. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An investigator seizes a computer that was involved in a crime. The suspect claims that the evidence was planted. Which forensic principle best helps to refute this claim by demonstrating that the evidence could only have been left by the suspect?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Locard's exchange principle
Locard's exchange principle states that every contact leaves a trace. In digital forensics, this means the suspect's interaction with the computer—such as typing, accessing files, or connecting peripherals—will leave unique digital artifacts (e.g., registry keys, prefetch files, USB device serial numbers, or browser history). By demonstrating that these artifacts could only have been created by the suspect's specific actions or device, the investigator refutes the claim of planting.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Locard's exchange principle
Why this is correct
Locard's principle asserts that every contact leaves a trace, supporting that the suspect's interaction with the evidence is inevitable.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Hearsay rule
Why it's wrong here
Hearsay rule concerns out-of-court statements, not physical evidence.
✗
Best evidence rule
Why it's wrong here
Best evidence rule requires original documents, not about physical transfer.
✗
Chain of custody
Why it's wrong here
Chain of custody tracks handling but does not inherently refute planting; it can show if evidence was tampered with.
Common exam traps
Common exam trap: answer the scenario, not the keyword
EC-Council often tests whether candidates confuse chain of custody (a procedural safeguard) with Locard's principle (a scientific concept about trace evidence), leading them to pick chain of custody when the question asks about how evidence was left by the suspect.
Trap categories for this question
Command / output trap
Chain of custody tracks handling but does not inherently refute planting; it can show if evidence was tampered with.
Detailed technical explanation
How to think about this question
Locard's principle in digital forensics extends to artifacts like NTFS $UsnJrnl change journal entries, Windows Event Logs (e.g., Event ID 4663 for file access), and USB device descriptors (VID/PID/serial) stored in the registry under SYSTEM\CurrentControlSet\Enum\USB. For example, a suspect's USB drive will leave a unique serial number in the system, and file timestamps (MAC times) can show creation/modification patterns inconsistent with planting.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CHFI exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CHFI question in full detail.
Computer Forensics Fundamentals and Process — This question tests Computer Forensics Fundamentals and Process — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Locard's exchange principle — Locard's exchange principle states that every contact leaves a trace. In digital forensics, this means the suspect's interaction with the computer—such as typing, accessing files, or connecting peripherals—will leave unique digital artifacts (e.g., registry keys, prefetch files, USB device serial numbers, or browser history). By demonstrating that these artifacts could only have been created by the suspect's specific actions or device, the investigator refutes the claim of planting.
What should I do if I get this CHFI question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which of the following principles states that when two objects come into contact, there is a transfer of material between them?
easy
A.The best evidence rule
✓ B.Locard's exchange principle
C.The chain of custody
D.The hearsay rule
Why B: Locard's exchange principle is a foundational concept in forensic science, including digital forensics, where every contact leaves a trace.
Last reviewed: Jun 30, 2026
Question Discussion
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This CHFI practice question is part of Courseiva's free EC-Council certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CHFI exam.
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