The clients state: “On his second visit to the apartment, the crime scene cleaner and pest controller took about 3 - 5 specimens of the flies from the large room to have them identified by a biologist friend. We were not informed of the results of the investigation.” The landlord is said to have stated: “An expert confirmed to us that these flies must have come from outside and could not have developed in the apartment.” This statement is partly correct: The insects may have flown into the apartment from outside because they were attracted by the corpse odor serving as an attractant for these insects. They do not necessarily have to have developed there. They can also “only” feed or lay eggs on putrefying tissue. The presence of the skin beetles and adult flies indicates that the colonization/ flying of insects into the apartment, which was either littered with animal meat or had a human corpse, had been taking place for some time: These are so-called late corpse colonizers. All of the insects we examined only occur at corpse sites with decomposing corpses or in environments with a high meat content in old waste (animal or human corpse parts).
DISCUSSION
The insects studied here are either corpse colonizers or are clearly associated with decomposition processes or animals attracted by them.
We are not aware of any odor that is similar in composition to the type of corpse odor present here. A similar odor can occasionally arise from mountains of garbage, which must then consist mainly of meat scraps. Only then does this odor develop, and then only after sufficiently long “maturing”. The time required for this depends on the temperature: The warmer, the faster. Since the apartment in the video sent to us does not appear to be full of garbage, but empty, there would have to have been a large quantity of garbage with a high meat content.
The ammonia test is triggered by the presence of decomposable substances, not by “normal” wood floors or pieces. This shows that decomposition fluid (and not coffee) must have penetrated the floorboards.
We have a video from the apartment which shows that there are cracks in the floor, including where the body is supposed to have been lying. Decomposition fluid and pieces of tissue from the corpse may have entered the area under the floorboards through these cracks (puddle of fluid). Cadaveric fluid can penetrate the actual wood of unsealed floors and then remain there or under the wooden floorboards owing to the adhesive properties of the semi-liquefied cadaveric material.
From time to time, these kinds of contaminated floors are sealed to “encapsulate” the odor or treated with chemicals to dissolve or mask the odor (for example with the raspberry odor of Maskomal or similar). However, it makes more sense to remove the source of the odor; this is comparable to used baby diapers, which are also thrown away or cleaned and not covered up in order to mask the odor.
The collective occurrence of the insects from the apartment samples certainly indicates the presence of at least decomposition fluid, the odor of which attracted the animals. The putrefactive liquid must have been in the wooden floor in sufficient quantity and presumably over a longer period of time, otherwise only blow flies would be found, which colonize corpses at an early stage. Skin beetles and chalcid wasps appear as later corpse colonizers [28]: Carpet beetles and their larvae use dried organic tissue and dead insects (such as flies) as a food source. However, they are less commonly found in apartments with corpses and piles of garbage, as the soiled areas are usually cleared and cleaned quickly. Chalcid wasps in particular are then naturally no longer attracted: They colonize the juvenile stages of other insects.
The absence of blow fly larvae and their pupae in the samples and on the photos indicate that there is now no fresh, new organic material available for the blow fly larvae to feed on. None was found anyway.
As blow fly larvae usually seek out dark and narrow “hiding places” to pupate, fly pupae and larvae could also be found under floorboards and behind carpet rails. This can occur from time to time and sometimes leads to strange occurrences of flies for the residents. For example, an apartment can be cleared and cleaned, but the pupae of the flies are still hidden in cracks and the flies hatch from the pupae later (see case 2 „Empty Apartment“ [29]).
The “mixture” of dead flies, beetles and chalcid wasps in the apartment concerned here means that the animals were attracted by the smell of corpses and died in the apartment or that there was sufficient food (including corpse fluid). It is irrelevant whether these flies developed in the apartment (from larvae) or whether adult insects have flown into the home. The main reason for their appearance is that they are attracted by the smell of decay.
Conflict of interest
The authors declare that they have no conflict of interest.
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