Movies and TV programmes based on the miracle of forensic science and pathology are leading juries to rely on weak evidence in the courts.
The wonders of science applied in the popular police and detective series are just fiction, according to real-life crime scene investigators.
Take enhancing CCTV images.
Most of these images are hazy and the people in the frame are almost unrecognisable.
But the TV investigator blows up the image until they can see pertinent details to identify the suspect from a reflection in a mirror.
Just not possible.
Finding the Phantom
“Zoom and enhance is just never going to happen. If you make CSI type TV programs, please stop doing it,” one forensic science told the BBC.
Analysing burn patterns at the scene of a fire is another pseudoscience.
Crime scene lecturer and author John J Lentini asked a trainee investigator what a burn mark meant at a crime scene.
“The answer was absolutely nothing,” he said. “Most of the time investigators turn up non-existent patterns.
The Phantom of Heilbronn is a CSI case that haunts investigators.
DNA traces of an unknown person were found at a huge number of crime scenes across Europe.
Wrong questions get wrong answers
Detectives worked on the theory that they had a serial killer striking across the continent.
But it turned out there was no serial killer.
The DNA swabs were accidentally contaminated by a worker in the factory where they were made and it was his DNA that was turning up everywhere.
Experienced investigators know that crime scene investigation can only tell scientists what they ask, but if they ask the wrong questions or have a bias towards the answer they are looking for, then they will often get the wrong answer.
The data does not lie but the judgment applied to the analysis can be skewed.
“No one knows how many innocent people have been convicted based on junk forensic science, but research recommends substantial funding increases to enable labs to conduct experiments to improve the validity and reliability of the many forensic subfields,” said forensic expert Michael Shermer in the Scientific American.