TEXAS DPS CRIME LABORATORY ANALYST EXAM – PRACTICE QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF.
Core Domains
Forensic Biology and DNA Analysis
Controlled Substances and Toxicology
Firearms and Toolmarks
Trace Evidence and Materials Analysis
Crime Scene Processing and Evidence Handling
Quality Assurance and Accreditation Standards
Legal Procedures and Expert Witness Testimony
Laboratory Safety and Biohazard Protocols
Ethics and Professional Conduct
Introduction
This comprehensive practice assessment is designed to prepare candidates for the rigors of the Texas
Department of Public Safety (DPS) Crime Laboratory Analyst examination. The exam evaluates a candidate's
mastery of forensic science principles, laboratory methodologies, and the stringent legal requirements governing
evidence in the state of Texas. Through a blend of multiple-choice and complex scenario-based questions, the
assessment tests foundational theory alongside real-world application. Candidates are challenged to demonstrate
critical decision-making skills, adherence to ethical standards, and a deep understanding of quality control
protocols necessary for maintaining the integrity of forensic results within the criminal justice system.
Section One: Questions 1–100
1. Which of the following best describes the "chain of custody"?
,A. The process of testing evidence for biological fluids.
B. A chronological documentation showing the seizure, custody, control, and transfer of evidence.
C. The legal statute that defines the sentencing for a specific crime.
D. The hierarchy of command within a forensic laboratory.
🟢 B. A chronological documentation showing the seizure, custody, control, and transfer of evidence.
🔴 RATIONALE: The chain of custody is a foundational legal requirement that ensures evidence has not been
tampered with or substituted from the moment of collection until it is presented in court.
2. In DNA analysis, what is the primary function of the Polymerase Chain Reaction (PCR)?
A. To measure the weight of a DNA molecule.
B. To destroy unwanted cellular debris in a sample.
C. To amplify specific regions of DNA for further analysis.
D. To sequence the entire human genome.
🟢 C. To amplify specific regions of DNA for further analysis.
🔴 RATIONALE: PCR allows forensic scientists to create millions of copies of specific DNA markers from a very
small or degraded sample, making it possible to generate a DNA profile.
3. When collecting a bloodstain on a non-porous surface like glass, which method is generally preferred?
A. Scraping the dried stain into a paper bindle.
B. Using a wet swab followed by a dry swab (double swab technique).
C. Cutting the glass and submitting the entire pane.
D. Using adhesive lifting tape.
,🟢 B. Using a wet swab followed by a dry swab (double swab technique).
🔴 RATIONALE: The double swab technique maximizes the recovery of DNA from non-porous surfaces by
rehydrating the sample with a wet swab and capturing the remaining moisture with a dry swab.
4. A "controlled substance" is defined under the Texas Controlled Substances Act based on what primary
criteria?
A. Its color and physical state.
B. Its market value and street name.
C. Its potential for abuse and recognized medical use.
D. The age of the individual in possession of the substance.
🟢 C. Its potential for abuse and recognized medical use.
🔴 RATIONALE: Substances are categorized into schedules based on their likelihood to cause addiction or harm
versus their accepted clinical applications.
5. What is the standard measurement used to determine the caliber of a firearm?
A. The length of the barrel.
B. The weight of the projectile in grains.
C. The diameter of the bore of the rifled firearm.
D. The total length of the cartridge casing.
🟢 C. The diameter of the bore of the rifled firearm.
🔴 RATIONALE: Caliber refers to the internal diameter of the barrel, measured between opposite lands or
grooves.
, 6. Which constitutional amendment protects individuals against unreasonable searches and seizures?
A. Second Amendment
B. Fourth Amendment
C. Fifth Amendment
D. Sixth Amendment
🟢 B. Fourth Amendment
🔴 RATIONALE: The Fourth Amendment is critical in forensic science as it dictates the legality of how evidence is
obtained at a crime scene.
7. In toxicology, the term "LD50" refers to:
A. The dose that is lethal to 50% of the tested population.
B. The legal limit of blood alcohol concentration (0.050).
C. A drug that has been diluted by 50%.
D. The 50-minute window for testing a sample after ingestion.
🟢 A. The dose that is lethal to 50% of the tested population.
🔴 RATIONALE: LD50 (Lethal Dose 50) is a standard measure used to characterize the acute toxicity of a
substance.
8. A laboratory analyst discovers a mistake in their final report after it has been issued. What is the correct
ethical and professional action?
A. Shred the original report and issue a new one with the same date.
B. Delete the electronic record and ignore the error if it is minor.
(VERIFIED ANSWERS) PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF.
Core Domains
Forensic Biology and DNA Analysis
Controlled Substances and Toxicology
Firearms and Toolmarks
Trace Evidence and Materials Analysis
Crime Scene Processing and Evidence Handling
Quality Assurance and Accreditation Standards
Legal Procedures and Expert Witness Testimony
Laboratory Safety and Biohazard Protocols
Ethics and Professional Conduct
Introduction
This comprehensive practice assessment is designed to prepare candidates for the rigors of the Texas
Department of Public Safety (DPS) Crime Laboratory Analyst examination. The exam evaluates a candidate's
mastery of forensic science principles, laboratory methodologies, and the stringent legal requirements governing
evidence in the state of Texas. Through a blend of multiple-choice and complex scenario-based questions, the
assessment tests foundational theory alongside real-world application. Candidates are challenged to demonstrate
critical decision-making skills, adherence to ethical standards, and a deep understanding of quality control
protocols necessary for maintaining the integrity of forensic results within the criminal justice system.
Section One: Questions 1–100
1. Which of the following best describes the "chain of custody"?
,A. The process of testing evidence for biological fluids.
B. A chronological documentation showing the seizure, custody, control, and transfer of evidence.
C. The legal statute that defines the sentencing for a specific crime.
D. The hierarchy of command within a forensic laboratory.
🟢 B. A chronological documentation showing the seizure, custody, control, and transfer of evidence.
🔴 RATIONALE: The chain of custody is a foundational legal requirement that ensures evidence has not been
tampered with or substituted from the moment of collection until it is presented in court.
2. In DNA analysis, what is the primary function of the Polymerase Chain Reaction (PCR)?
A. To measure the weight of a DNA molecule.
B. To destroy unwanted cellular debris in a sample.
C. To amplify specific regions of DNA for further analysis.
D. To sequence the entire human genome.
🟢 C. To amplify specific regions of DNA for further analysis.
🔴 RATIONALE: PCR allows forensic scientists to create millions of copies of specific DNA markers from a very
small or degraded sample, making it possible to generate a DNA profile.
3. When collecting a bloodstain on a non-porous surface like glass, which method is generally preferred?
A. Scraping the dried stain into a paper bindle.
B. Using a wet swab followed by a dry swab (double swab technique).
C. Cutting the glass and submitting the entire pane.
D. Using adhesive lifting tape.
,🟢 B. Using a wet swab followed by a dry swab (double swab technique).
🔴 RATIONALE: The double swab technique maximizes the recovery of DNA from non-porous surfaces by
rehydrating the sample with a wet swab and capturing the remaining moisture with a dry swab.
4. A "controlled substance" is defined under the Texas Controlled Substances Act based on what primary
criteria?
A. Its color and physical state.
B. Its market value and street name.
C. Its potential for abuse and recognized medical use.
D. The age of the individual in possession of the substance.
🟢 C. Its potential for abuse and recognized medical use.
🔴 RATIONALE: Substances are categorized into schedules based on their likelihood to cause addiction or harm
versus their accepted clinical applications.
5. What is the standard measurement used to determine the caliber of a firearm?
A. The length of the barrel.
B. The weight of the projectile in grains.
C. The diameter of the bore of the rifled firearm.
D. The total length of the cartridge casing.
🟢 C. The diameter of the bore of the rifled firearm.
🔴 RATIONALE: Caliber refers to the internal diameter of the barrel, measured between opposite lands or
grooves.
, 6. Which constitutional amendment protects individuals against unreasonable searches and seizures?
A. Second Amendment
B. Fourth Amendment
C. Fifth Amendment
D. Sixth Amendment
🟢 B. Fourth Amendment
🔴 RATIONALE: The Fourth Amendment is critical in forensic science as it dictates the legality of how evidence is
obtained at a crime scene.
7. In toxicology, the term "LD50" refers to:
A. The dose that is lethal to 50% of the tested population.
B. The legal limit of blood alcohol concentration (0.050).
C. A drug that has been diluted by 50%.
D. The 50-minute window for testing a sample after ingestion.
🟢 A. The dose that is lethal to 50% of the tested population.
🔴 RATIONALE: LD50 (Lethal Dose 50) is a standard measure used to characterize the acute toxicity of a
substance.
8. A laboratory analyst discovers a mistake in their final report after it has been issued. What is the correct
ethical and professional action?
A. Shred the original report and issue a new one with the same date.
B. Delete the electronic record and ignore the error if it is minor.
