Solving Murders with Microbes

NDSU Microbiology
by NDSU Microbiology

Microbes Could Solve Murder Cases…Impossible! Right?

Guest Blogger: Marcie Bachler, Undergraduate in Microbiology

I love TV shows like CSI. My favorite one was CSI Las Vegas, the original, the one with Grissom. I loved how he would sit out in the cold and watch flies and their reaction to a decomposing pig body. I want to be like the investigators on the shows, like him, but without all of the bugs and insects. Now science is getting closer to me being able to do everything they do, find the time of death, the murder weapon and possibly even confirm alibis just with the help of microbes.

You should know that I am a microbiology student and love to learn about how some bacteria can only grow in certain conditions while others can grow just about anywhere. However, I have always been curious about how crime scene investigations can move forward with evidence from a sample of dirt or bruise pattern while other cases fall apart because of a partial fingerprint and a solid alibi. This is why I am pursuing a minor in criminal justice.

I want to be able to help my community and the family members that want answers about their passed away loved ones. The only field I can think of that combines my passion for microbiology and criminal justice is forensics. One group of scientists, in particular, is doing exactly what I want to do someday. and a group of scientists outside of Huntsville, Texas are doing just that.

In this group of Huntsville, Texas scientists there are ecologists who study the environment and entomologists who study insects. Their goal is to figure out if there is a “microbial clock” on decomposing bodies. These scientists use dead bodies, ones that have been donated to science, and they lay them out on the ground (in different areas) and “scrape” their skin in specific places to gather bacteria samples. After that, they put dirt from that location of the body onto them. Then they come back and take samples from time to time in the same scraped skin places to see if there is any pattern or way to predict the microbial growth as time goes on.

If they are able to figure this out, then they think one day there may be a way we can tell the difference between a natural death and a forced death, all with the help of microbial populations on a person’s skin! In addition, if scientists are able to categorize which types of microbes are connected to dead bodies, then investigators might be able to pinpoint where an unmarked grave is by the types of microbes in the soil.

But the science that has already started to be looked at and found to be leading somewhere is “microbial fingerprint(s).” People have their own types and quantities of microbes on their skin, which could lead to possibly solving murder cases by swabbing the murder weapon against a suspect and seeing if the microbes match. This could potentially replace fingerprints being the main source of guilt.

This same science could be used in the future to prove or disprove a person’s alibi. In essence, the microbes on a person’s skin could be used to determine if a person travelled to a certain city or state.

These types of techniques may not be developed and treated as real evidence for awhile, but for now they are curious things to consider. Perhaps instead of dusting a whole room for fingerprints or just an approximate range of when a body is dead microbiologists will be able to make investigations go smoother, quicker and be more scientific based.

Maybe this will mean that fewer innocent people will go to jail, or that family members of the deceased will get the answers they have been looking for with actual backed up data and not just on a whim.

But I wonder if we have to wait for bacteria samples to grow on a culture would be quicker than searching for a fingerprint? Or would the court system ever consider that each person has a different set of microbes on their skin or if they would just consider the evidence circumstantial?

These experiments are just in their beginning stages, but scientists at the University of Colorado can narrow the range of days a mouse has been dead using just bacteria. So we could be closer to finding a “microbial clock” of decomposition than previously speculated.

Right now, all I can think about is graduating and starting to help out with experiments like these.

This entry is part of the fall MICR 354 scientific writing students' blog series.