When a murder or some other crime is committed, insects are the first to arrive at the crime scene, even before the police show up, and in Spain these small creatures have helped to solve 150 crimes over the past 10 years.
The National Police Corps is a pioneer in forensic entomology in Spain and its laboratory, set up 10 years ago in the Scientific General Police Headquarters, annually handles 30 cases, not only murders but also drug trafficking, vehicle theft and even acts of terrorism.
The main application of forensic entomology, however, has been and continues to be determining with a good bit of precision the time of death of murder victims.
The study of creatures that live in bodies - diptera (flies) and coleoptera (beetles), which take up residence in and feed on decomposing corpses - allows the police to zero in on suspects or reject alibis.
In addition to determining the time of death, investigators analyse the animals that have fed on the body looking for drugs, poisons or powder residue that could shed light on the cause of death.
Sometimes, forensic technicians also examine the stomachs of the larvae found at the alleged crime scene looking for DNA from the victim, a technique that has served, in some cases, to identify a dead person whose body has never turned up, since it was transported elsewhere and hidden after death.
In the past few years, the forensic entomology laboratory has broadened its study to include crimes such as drug trafficking to find drug smuggling routes or the location of clandestine drug labs.
Police also analyse the insects adhering to vehicles suspected to have been used in crimes or even in terrorist acts to determine the itinerary followed by those vehicles before they were discovered by the police.
In incidents of abuse or abandonment of minors and elderly people, entomology can also help police when insects have become parasites on the bodies of the victims.
The forensic entomology lab, which is headed by two biologists, has a wide-ranging catalog of identified insect species that keeps growing day-after-day thanks to live samples that researchers gather "in situ" and that later are raised at the facilities of the Canillas police complex in Madrid.