DNA Fingerprinting in a Criminal Investigation

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DNA Fingerprinting Process

The first step in DNA fingerprinting is to break open the sample cells and collect the DNA. Next, many copies of the DNA are made using polymerase chain reaction (PCR).

To get the DNA fingerprint:

  • All of the DNA is broken into pieces at certain locations. This is done by chemicals (enzymes) that break each DNA strand at the same place.
  • The DNA pieces are placed at the top of a special gel held in a frame.
  • An electric current is applied to the gel. The current separates the DNA into bands of identical pieces. This process is called electrophoresis.
  • The band pattern is transferred to a nylon membrane containing a radioactive chemical. The chemical makes the bands show up clearly.

For a criminal investigation, photos of the criminal and suspect DNA are compared. The results in this case show that the suspect is not the criminal.

ByHealthwise Staff
Primary Medical Reviewer Kathleen Romito, MD - Family Medicine
Specialist Medical Reviewer Siobhan M. Dolan, MD, MPH - Reproductive Genetics

Current as ofFebruary 20, 2015

Current as of: February 20, 2015

Author: Healthwise Staff

Medical Review: Kathleen Romito, MD - Family Medicine & Siobhan M. Dolan, MD, MPH - Reproductive Genetics