If you watch police shows or courtroom dramas on TV, you would think that DNA evidence comes up in every case. In many cases, DNA evidence is available to help prove guilt or innocence, but it is not a magical identification tool that shows and movies make it out to be.
Murder cases are the most serious crimes there are, so DNA evidence is often collected. However, it does not need to be processed if there is sufficient evidence to identify the defendant and convict them without it. In any case, DNA evidence is most commonly used to help confirm that a defendant was at the scene of the crime or that a victim’s DNA was found on the defendant or on the defendant’s items or property. This makes DNA more circumstantial than one might expect.
For help with your case, call the Utah murder and manslaughter defense lawyers at Overson Law at (801) 758-2287.
Ways that Police and Prosecutors Use DNA Evidence in Murder Cases in Utah
DNA is quite unique to each person, and the testing that we use today can generally match DNA evidence with a very high level of certainty that the samples match. This sets up the general way that DNA evidence is used and collected: with two samples taken from two sources and checked to see if they match. Ultimately, that ends up being used in murder cases in the following ways:
Defendant’s DNA on Victim (or Vice Versa)
One way that DNA can be checked is to take a sample from the victim or defendant’s body. If a murder also involves rape or sexual assault, there might be semen or other DNA from the assailant on the victim. Similarly, if the victim scratched or fought off a killer, they might have gotten some of the defendant’s DNA under their nails.
If samples from the other person’s body match, then it becomes quite likely that the defendant was physically close to the victim or that the victim and defendant had a physical altercation, but this does not necessarily prove that the defendant killed them. Instead, this can only go so far as to show that there was an interaction – maybe a confrontational one – but the prosecution will still need to prove motive, how the victim was killed, etc.
Victim’s DNA in Defendant’s Car/House/Etc.
If the police suspect the victim was attacked or killed at another location and then moved, they will often look for the victim’s DNA at the original location where they suspect an attack or killing happened. This could be from blood at the scene of the killing or in a car used to transport the victim.
If the victim’s blood or DNA is in your house or car, it is going to be incredibly suspicious and point to you being the one to kill them – or at least show that you witnessed the attack/killing and perhaps moved the victim before or after they died.
Identifying Victim
Sometimes the state of the victim makes identifying them difficult. Visual identification, dental records, and DNA are the typical tools used to tell who the victim is, and DNA is often a last resort or used when there are no hints at the person’s identity. This often requires “running” the victim’s DNA and hoping it matches someone reported missing, as discussed below.
Identifying Defendant
When there are no leads on who the defendant might be, it might be possible to “run” the defendant’s DNA – more on that process below.
Excluding Suspects
If a suspect’s DNA does not match the killer’s DNA, then DNA can actually be used to show someone was innocent. This is often used in post-conviction cases to get convictions overturned when the original DNA evidence was not tested properly or was unavailable.
Can Police Check DNA Against a Database in Utah?
Fingerprints have been taken from arrestees for decades, and storing these in a central FBI database (IAFIS) as well as independent state databases often allows police to put in a fingerprint they found at the scene of a crime and run a check to see if it matches any prints in these databases. If they get a “hit” on the print, they can often identify someone who was at least at the location or touched something in the location, giving them grounds to bring that person in for questioning. Can they do the same with DNA?
For DNA in the U.S., we use a system called CODIS – the Combined DNA Index System – as a database for DNA. This allows a similar search, where a DNA sample’s record is put into the system and then checked to see if there is a match.
DNA can be input from an unknown defendant or an unidentified defendant. Often, people who are reported missing also have their DNA added to this system, hoping that if an unidentified person or body is found, they can match them through CODIS. People with previous criminal cases involving DNA or who have been ordered to give a DNA sample for their record will also be in this database.
In any case, identifying someone with DNA this way has the same flaws and problems with other potential DNA evidence: that it only proves the DNA was there.
DNA as Circumstantial Evidence in Utah Homicide Cases
We often discuss evidence as “circumstantial” as a polite way of saying it is “weak” evidence, but this is not what circumstantial evidence means. Instead, evidence is circumstantial if it goes to explaining the circumstances surrounding an event rather than being “direct” evidence of what happened (such as a witness seeing the crime happen).
A common example is coming out of a building and seeing that everything is wet; that is circumstantial evidence that it rained. We know that it might have been something else – maybe someone sprayed a hose or a sprinkler in the area – but if there are clouds in the sky and other matching circumstantial evidence, rain is probably the most likely explanation.
DNA evidence works in a similar way. It can show you that the person’s DNA was there, meaning that they were likely there to leave the DNA there. However, there are other potential explanations based on innocent excuses as to why the suspect’s DNA was on the victim (e.g., if they had consensual sex with the victim the day before the murder) or why the victim’s DNA was at the defendant’s house (e.g., they nicked themselves cutting vegetables in the defendant’s kitchen).
DNA evidence is strong and hard to trick or fake, but it is not perfect; police still need to prove other facts and motivations to win their case.
Example Case
In a 2011 murder, a woman named Uta von Schwedler was discovered dead in her bathtub with lethal levels of Xanax in her system, unexplained cuts, and someone else’s tissue under her fingernails in conjunction with potential signs of a struggle. However, the testing of the DNA showed inconclusive results – i.e., there wasn’t enough there to match the DNA to anyone.
This meant that the prosecution wanted to say the evidence didn’t exclude the defendant, and the judge permitted them to say that. It arguably couldn’t have included him in the suspect list either, and the defendant, after his conviction, maintains that the DNA evidence was improperly admitted for this kind of argument.
Call Our Utah Murder and Manslaughter Lawyers Today
For help with your case, call the Layton, UT murder and manslaughter lawyers at Overson Law at (801) 758-2287.
