'Diatom Detectives' to help solve crime

Microscopic algae on beaches and along coasts could help detectives to track down criminals, according to ground-breaking research in Liverpool.

It has been known since the days of Sherlock Holmes (or his creator Arthur Conan Doyle) that environments can leave traces of physical evidence on a perpetrator, a weapon or a body. But tracing dust, hair, fibres, bacteria and other evidence in bodies of water, seas, lakes is extremely difficult.

Now forensic scientists at Liverpool John Moores University are examining tiny naturally occurring algae called diatoms which attach themselves to physical evidence and provide proof of a location, time or event.

Diatoms are hugely diverse with an estimated 20,000 species worldwide of all different colours, shapes and ornamentation and are virtually indestructible. Crucially for forensics, they also build very specific communities in specific locations.

“The beauty of diatoms is that they are so abundant and can be mapped to certain places and environments, meaning they are almost like eyewitnesses,” explained Dr Kirstie Scott, of LJMU’s Forensic Research Institute. 

Dr Scott, alongside PhD student Alice Stevens, took water samples from six locations across Merseyside - Thurstaston Beach, Crosby Marine Lake, West Kirby Marine Lake, New Brighton Beach and Speke and Garston coastal reserve - and found a distinctive diatom ‘species assemblage’ in each location.

Her team also submerged items of clothing at the locations and later tested them for diatoms.

“Essentially, we were able to associate each item of clothing to a location, such that you could take a random coat or skirt and prove that it had been by the shore at Thurstaston or Speke.

“Aquatic systems are complex and notoriously difficult for forensic scientists to analyse, so using diatoms as a reliable tool would have a huge impact for crime scene investigation.”

She says, they also found one diatom which had only been identified once before in the UK and it was previously thought to be specific to the Pacific region.

The research, published in Forensic Science international, and reported in the national press, is the first forensic study to investigate the potential of diatoms in marine crime scene scenarios.

Image: Alice Stevens and Kirstie Scott take forensic samples at Thurstaston Beach. Picture: Neil Grant