In honor of the fact I’m doing some forensic DNA consulting, I’m allowing people to pick my brain about real-life forensic science. Simply ask your question in the comments, and I’ll either answer it there, or expand in a blog post. We’ll go as long as you guys have an interest.
The question for today was submitted by Loraine Kemp, a fantastic writer and illustrator. She wants to know,
Did you ever have to report on a case where the evidence was presented to you/the lab with a story of what had happened in the crime scene and you had to disagree based upon your findings?
The short answer is, yes. That happens pretty often. If you’re a good forensic scientist (one that is not biased), you don’t have a vested interest in the outcome of a case. It’s your job to analyze the evidence to the best of your ability, and then report those findings back to law enforcement to help them do their job. The great thing about DNA is that while it is a powerful tool that can be used to link people to a crime scene, it is equally powerful in exonerating individuals who are under suspicion.
Let’s say that a woman was attacked by an acquaintance. Maybe she had just met him and was at his apartment. She manages to get away after he falls asleep by taking his keys and leaving in his car. She reports the assault (or attempted assault) to the police. Maybe she goes to the hospital and they collect her clothing and biological evidence from her body to submit to the lab.
What happens if the man (now a suspect) calls the police department to report his car stolen?
What happens if law enforcement finds out that this woman has made multiple claims of being attacked by different men and taking their cars as a means of escape? Or that she claims she was assaulted to cover up her serial joyriding fetish?
Let’s say that a certain biological fluid was found on the woman’s shirt by the laboratory (use your imagination, I’m trying to be PG here). If the biological fluid was consistent with the DNA of the man, what would that tell you? Would that mean she had been assaulted by him? Or might it mean that they engaged in some mutually consensual activities before she stole his car?
What if the DNA results showed that the biological fluid was NOT from the man with the car? Would that mean that he didn’t assault her? What if there were multiple stains on the woman’s shirt, and each produced a different male profile, neither consistent with our alleged attacker? What would you think then?
Hopefully you see the point I’m trying to make. There are two sides to every story. Complainants don’t always tell the truth. Maybe they’re embarrassed about what happened. Maybe they’re mad at an ex-boyfriend and want to try to get him in trouble. Maybe they’re trying to divert attention from their own illegal activity. Or maybe they’re underage and brought to the hospital by a concerned parent. You never know.
The best thing to do is analyze the evidence you have and report the results you get. Forensic scientist don’t determine guilt or innocence; that’s the purview of the jury should the case get that far.
QUESTIONS/COMMENTS? WHAT ELSE WOULD YOU LIKE TO KNOW?