4 Case Scenarios for Crime Scene Investigation
Case Scenario #1: The Wrong Race Investigation
In a serial killer case that lasted for nearly two years, police had received countless tips and several eyewitness accounts. Eyewitnesses can be your best friend in some cases and your worst enemy in others. The following case illustrates the pitfalls of trusting eyewitness accounts over scientific evidence.
THE CASE
The perpetrator’s DNA linked him to six homicides within a fairly well defined area. His DNA profile could not be found in the national DNA database of registered offenders and eyewitness reports lead investigators to believe that he was most likely to be a Caucasian male. This belief lead to the subsequent collection and analysis of hundreds of DNA samples from men in the area who fit the description.
Figure 1: Sketches released to the media.
THE COST
When trying to determine the cost of an investigation it is easy to forget how quickly an agency’s budget can be exhausted. Chasing leads that turn out to be nonsense can be the largest waste of a department’s budget and in a serial killer case those expenses can grow exponentially. In some cases the cost of not knowing your suspect quickly, can be life itself.
THE SOLUTION
Using DNAWitness™ investigators were able to narrow the field of suspects to individuals who fit the profile and exclude whole populations of people. Within two months of receiving the DNAWitness™ results, they had a suspect in custody. This suspect’s CODIS profile matched the profile linking many of his victims. The investigators who decided to utilize this innovative bio-intelligence test had essentially given themselves a “fuzzy photo” of their suspect.
Figure 2: DNAWitness™ profile from crime scene DNA and interpretation of how the suspect may appear.
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Case Scenario #2: Conflicting Eyewitnesses
In a cold case where a man was seen fleeing the scene in darkness, police interviewed several eyewitnesses and were told that the man was both “black” and “white”. Many factors can play into how an eyewitness perceives what has happened and who was committing the crime. The following case illustrates the pitfalls of trusting eyewitness accounts over scientific evidence.
THE CASE
The perpetrator’s DNA linked him to a double homicide in a residence. His DNA profile could not be found in the national DNA database of registered offenders and with conflicting eyewitness accounts of what the suspect looked like, investigators could not rule out two major populations of people.
Figure 1: Sketches from conflicting eyewitnesses of a man fleeing the scene
THE COST
It may be difficult to measure the overall cost of time and effort put into chasing false leads. Depending on the size of the investigation and the number of people working on the case, the costs associated with chasing false leads could buy a new squad car in some cases. The time spent on false leads can effect time needed to solve other cases, possibly causing a cascade effect from case to case of missed opportunities caused by faulty eyewitnesses. This makes calculating the cost that it may have on other cases even more difficult.
THE SOLUTION
The investigators were about to begin swabbing possible suspects in both populations when they decided that using a bio-intelligence test such as DNAWitness™ would greatly reduce the amount of hours needed. The test was not only able to confirm the ancestry profile of the person who left the DNA at the crime scene but the DNAWitness™ test also provided photographs from a database of tested individuals that have a similar profile. The photographs will not be of the suspect but of volunteers who have provided images so that investigators will have a better idea of what the DNAWitness™ profile means.
Figure 2: DNAWitness™ profile from crime scene DNA and interpretation of how the suspect may appear.
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Case Scenario #3: Victim’s Remains
Identifying victims from the remains can be difficult, especially if the body is in an advanced state of decomposition or parts are missing. The fingerprints and the dental records can prove invaluable in determining the identity of the victim but what if it’s not possible to use these more traditional means?
THE CASE
The torso of a woman was found in a wooded area but her other body parts were never found. The Jane Doe was initially thought to be Caucasian by crime scene investigators. The medical examiner, when asked, inferred that she was “a possible Hispanic or Caucasian woman”. The population make-up in the area where the body was found may have played into this idea, being largely Hispanic.
Figure 1: Rendering of victim’s remains.
THE SOLUTION
The bio-intelligence provided by DNAWitness™ in this case was able to dispel the notions thought by both the investigator and the medical examiner. Using DNAWitness™ eliminated the guesswork and speculation about the ancestry of the victim. Jane Doe turned out to be a high percentage of East Asian. When presented with the example photographs from the database comparison, the investigator indicated that there was a much smaller East Asian community in his area.
Figure 2: DNAWitness™ profile from the torso and interpretation of how the suspect may appear.
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Case Scenario #4: No Good Leads
Usually the perpetrator of a crime gets caught because someone who knows about the crime decides to talk. In some cases though, all the leads are dead ends. These are the cases that become cold cases and wait for years for the criminal to strike again. Essentially waiting for fresh blood and new information to be injected into the investigation.
THE CASE
A family of four was brutally beaten and shot to death in their home in what appeared to be a home invasion. Months later, detectives found out that the perpetrator left his blood in several places at the crime scene. The family was from China and lived in a predominantly Asian community, which led to the speculation that the perpetrator may be East Asian. When the perpetrators blood made it from the crime scene to the lab, the lab was inundated with work and the sample analysis was stalled. Eventually the perpetrator’s DNA profile made it into CODIS, the national database of offender profiles, for comparison. There was no match.
THE SOLUTION
By using a bio-intelligence test like DNAWitness™ within a few weeks of the crime, you are affording yourself specific population data about your key suspect while the trail is still hot. This can save your investigation time and money. For example, if a trail of blood leaving the crime scene appears to be that of a potential suspect and DNAWitness™ is used to produce the profile below, the investigator need not question anyone appearing African American.
Figure 1: DNAWitness™ profile and interpretation of how the suspect may appear
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Case Scenario #5: Cold Case Files
Cold cases can span years and even decades without resolution. You have to ask yourself, “What is the mechanism that causes a case to go cold?” Of course there can be several factors, but chasing leads from faulty information or eyewitnesses can be the defining factor that allows a criminal to evade capture. After years of stagnation, some agencies are tackling these cases and finding that a good number of them can be solved with DNA. In fact, the National Institute of Justice makes grant money available specifically for solving cold cases.
THE CASE
In Small-town USA, a young Caucasian woman who liked to run with a rough crowd was raped and murdered over twenty years ago. At that time, DNA testing was not possible but evidence was collected from the woman’s body and semen was identified. Detectives suspected her boyfriend initially, who was Caucasian, but ruled him out. The general thought about the race of the perpetrator was that he was Caucasian because that’s who her social group was. When the cold case was resurrected, the suspect’s DNA profile was checked against the national DNA database with no luck.
THE SOLUTION
The detective now assigned to this case was looking for information that would come from the physical evidence. She realized that DNAWitness™ could tell her an important bit of information about the suspect, what he looks like. To her surprise, the profile came back a major percentage of Sub-Saharan African indicating that the suspect was not Caucasian. The output from the photo database also let her know what people with a DNAWitness™ profile similar to her suspect would look like. This information has brought new life in this decades old investigation.