I’ve grown tired of watching the same “true crime” plotlines over and over again on TV. I want the bad guys to be caught, but what I really want is more variation, more novelty, more…science. I would therefore like to pitch an idea for a new episode of a detective drama, an idea that is exciting, new, and best of all, completely plausible:
The protagonist is a detective, bent on investigating a potential homicide in a normally quiet, sleepy suburban town. A woman was discovered floating facedown in the local pond this morning and though the consensus is accidental drowning, she suspects foul play. What if the body was moved there after being drowned elsewhere, maybe in a bathtub or another lake? The townspeople ask, “How are you going to figure out where she drowned?” and she answers, “With the help of some crime-solving diatoms, my good citizens.”
This scenario may seem preposterous—diatoms are tiny, unicellular floating algae that are better known for their photosynthesizing ability and their siliceous cell walls than for any crime fighting ability. But I have evidence of its veracity! I present to you this intriguing video in which a kindly old man explains how diatoms did in fact help him to solve a murder case.
It turns out diatoms, which can be found in both marine and freshwater environments, are the linchpin in the field of forensic limnology. This type of criminal investigation uses the presence and species of diatoms in crime scene samples and on victims to help solve crimes. Varying aquatic environments have different concentrations of nutrients such as nitrate, phosphate, and silica that diatoms need to grow, and certain diatom species grow better than others under these different conditions. The types of diatoms you find in a stream in the middle of the woods would be very different from those you find in a sewer pipe, for example.
Diatoms come in a wide variety of shapes and sizes, from elongated cylinders to globular spheres, and this lets the trained eye identify species using a light microscope. Our aforementioned lady detective would compare the ratio of species types from the pond where the woman’s body was found to those from tissue samples and subsequently determine where the woman drowned. If a particular, rare diatom specie is found in the water there and in the woman’s tissue, it is a good indicator that she drowned in that environment.
There could be a scence where the townspeople squint incredulously at the detective and wonder, “Tissue samples? How do diatoms get inside tissue?” They also might grimace as she tells them that if someone drowns and breathes water into their lungs, any diatoms in that water will enter into that person’s bloodstream through alveolar exchange—the same method that delivers oxygen to your bloodstream. These diatoms, borne along in a different kind of current, can be deposited in the liver and kidneys as they filter the blood that passes through them. Forensic limnologists are able to take samples from this tissue and extract the diatoms from them.
So this gung-ho detective, in the climactic scene of the episode, promptly does just this and discovers that the diatoms in the woman’s liver do not match those of the pond where she was found, but instead match the diatom community of another pond a few miles away. She investigates further and finds that the pond is on property owned by a business group which turns out to be a front for an international criminal syndicate—the woman’s true killers. With the help of her trusty diatom sidekicks, the detective brings them to justice and the town is at peace once more.