ATTITUDE, MIND SET AND KNOWLEDGE
- Draw conclusions from insufficient facts.
- Quit a major case until you have exhausted every lead.
- Prematurely fix on a suspect, then stick with this suspect when the evidence doesn’t fit or points away from this person.
- Spend too much time investigating minor crimes without suspects or physical evidence.
- Spin or incorrectly interpret evidence in order to make it fit into your theory of the crime.
- Withhold evidence that tends to exonerate (evidence that points away from guilt) the subject of your investigation.
- Think that simply because someone is strange, or has a bad reputation, he or she should be elevated to suspect status.
CRIME SCENE INVESTIGATION
- Handle or even touch physical evidence before it is photographed. (In Los Angeles County, it is against the law for an investigator to touch a corpse without the permission of the coroner’s investigator.)
- Use bathroom or kitchen facilities at the scene of the crime, and do not smoke there.
- Allow anyone on the scene who has no immediate investigative reason to be on the site.
- Leave the crime scene until you are finished processing it.
- Investigate a fire scene for possible arson if you have not been specially trained in cause and origin detection. (Arson dogs are great, but they can’t take photographs, write reports, or testify in court.)
- Classify a fire scene death where the corpse has been almost completely consumed as spontaneous human combustion. (This form of extreme burning has been scientifically identified as the “wick-effect.”)
- Publicly offer monetary rewards for information leading to the arrest of a suspect. (It encourages citizens to withhold information until they can get paid for it; it invites an army of crackpots into your case, causing wasted time running down false leads; and it indicates that your investigation has hit the wall.)
- Make deals with jailhouse informants in return for information on your case.
- Employ a so-called truth detection device called the Psychological Stress Evaluator (PSE) or Computer Stress Evaluator. (These instruments have been proven less reliable than flipping a coin. In some states they are illegal.)
- Put much weight on eyewitness identifications. (Studies have shown that there is no correlation between accuracy rates and how certain the witness is of the identification.)
- Consult with forensic graphologists (graphology is the study of personality traits revealed in one’s handwriting).
- Utilize, as forensic document examiners, people with backgrounds in graphology.
- Pressure a reluctant eyewitness into a positive identification.
- Interview witnesses in groups.
- Ask leading questions.
- Interview children, particularly as potential sex abuse victims, without special training.
- Threaten witnesses with arrest if they lie to you.
- Interrupt a witness with questions when the interviewee is still telling his or her story.
- Interrogate anyone whose guilt you are not certain of.
- Have the subject write up his or her confession. That is your job.
- Wear a gun in the interrogation room.
- Lie about the existence of physical evidence unless as a last resort.
- Furnish the subject details of the crime only known to the police or the perpetrator.