Forensic evidence is a dramatic part of the criminal conviction process, and thanks to dozens of television shows celebrating the science, has become perhaps the aspect of criminal arrests that Americans know most about.
But forensics are far from infallible. Learn the basics of forensic evidence and what happens when a defendant is wrongfully convicted.
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Forensics of Criminal Defense – How Criminals are Caught!
Types of Evidence – Proving Guilt
Forensic evidence is circumstantial relating to the guilt of the defendant.
Direct: Evidence > Guilt.
Classic example: Eye witness testimony stating “I saw the defendant shoot the victim.” The jury does not have to make any inferences.
Circumstantial: Evidence > Inference > Guilt.
Classic example: Ballistics testing shows that the bullet that killed the victim was fired from the defendant’s gun. The jury infers that the defendant fired his gun.
Patent – Prints left at a crime scene that can be seen with the naked eye.
Latent – Prints left at a crime scene that require some sort of dusting or chemical application to be seen.
Plastic – Prints left at a crime scene that have been pressed into a soft surface.
Exemplar – Prints that have been taken by police.
Not a simple procedure.
99.9% of human DNA is the exact same in every person.
A small number of people carry 2 sets of DNA in their bodies. Known as genetic chimerism this condition has fooled DNA testing in court.
50% of mothers carry some of their children’s DNA in their blood decades after giving birth.
It has been proven possible to manufacture fake DNA evidence in a lab that could be used against a defendant.
Exonerated by DNA
There have been 273 exonerations by DNA evidence in the U.S. The true perpetrators were identified in 124 of those cases.
Half of those wrongly convicted in the U.S. have been compensated for thier wrongful incarceration by the state or federal government.
75% of DNA exonerated cases initially involved an eye witness misidentifying the accused.
50% of DNA exonerated cases initially involved improperly handled forensic evidence.
Famous Forensic Cases
Narborough, Leicestershire, England
Colin Pitchfork was found guilty of the rape and murder of 2 girls and became the first man to be convicted of a crim based on DNA profiling in 1986.
Florida and Colorado, USA
Bite marks, Fabric matching
Ted Bundy was suspected to have killed more than 30 people in the 1970s but there was little physical evidence to link him to any crime until a distinctive bit mark matching Bundy’s crooked teeth was found on one of his victims. Fabric threads from Bundy’s car were also found on another victim.
New Jersey, USA
Money tracking, Hand writing
In 1932 Bruno Hauptmann kidnapped the toddler son of aviator Charles Lindbergh and was paid a $50,000 ransom. The baby was found dead shortly after. Police tracked the numbers on the bills paid in the ransom to find Hauptmann, then matched his hand writing to that of the ransom note to seal the conviction.
Presented by Total Criminal Defense