In particular, the forensic literature shows that numerous problems and misdiagnoses may arise regarding a forensic medical postmortem examination [12]. There are many reasons for an incorrect diagnosis. In many cases, doctors concentrate solely on the corpse, neglecting the immediate surroundings on the scene where the body was found [4, 13].

Another common mistake that can lead to an incorrect diagnosis is to not undress the deceased during an external postmortem examination [6,7,8]. Another source of error is a lack of diligence of the doctor performing the external postmortem examination, with essential findings being overlooked [4, 6]. Furthermore, the lack of knowledge about pathognomonic or characteristic findings may also lead to an incorrect diagnosis [5,6,7,8, 13]. Even after a correctly performed external postmortem examination obtaining the diagnosis correctly can be difficult in cases with discrete or no findings, even after lightning strike [9, 14].

In unobserved accidents, the diagnosis “death by lightning” is made due to the inspection of the surroundings on the scene, the victim’s clothing, including the contents of pockets and jewelry, as well as the findings on the corpse.

For a long time, Lichtenberg figures were regarded as the only pathognomonic finding for the diagnosis “lightning injury.” However, more than 100 years ago, singed body hair of a lightning victim was already considered a very characteristic finding [15].

If an accident due to technical electricity (high voltage) is excluded, both the Lichtenberg figure and singed body hair are considered pathognomonic for a lightning strike. In addition, skin burns and bleeding from the ear canal may sometimes have other causes. There has not yet been a study on the incidence of occurrence of singed body hair after fatal accidents due to lightning in a larger study group.

In a study of 45 deaths from lightning strikes in Florida (USA), Wetli found singed body hair and/or skin burns in 41 (91.1%) of the victims [16]. Unfortunately, no differentiation was made between the two different findings. An analysis of 10 fatal lightning accidents in Australia showed 7 victims with singed body hair, especially head and pubic hair [17]. In a study from Mecklenburg-West Pomerania singed body hair was found in 2 of 4 deceased due to lightning strike [3]. Lifschultz and Donoghue had similar findings in one out of five lightning strikes with fatal consequences [18].

Until the present study, there were no data for larger case numbers of fatal victims due to lightning strike with the occurrence of singed hair.

Of the 270 fatal accidents caused by lightning with information about diagnostic findings, singed hair was documented about five times more frequently than Lichtenberg figures in this study with 129 cases. This result confirms the assumption, based on the small number of cases so far, that after a fatal accident caused by lightning, regarding the pathognomonic findings, singed hair occurs considerably more often than Lichtenberg figures (Table 3).

In addition to the significantly more frequent occurrence, the singed body hair in relation to Lichtenberg figures has two other advantages for the diagnosis. Singed body hair does not disappear after a few hours as a finding and is also easily detectable in victims with darker skin color [19].

On the one hand, skin burns may be caused by other causes, however on the other hand, for example, they can show such characteristic findings due to lightning entry and exit marks that they must be regarded as proof of a lightning strike after a high-voltage accident due to technical electricity has been excluded.

Another finding on an external postmortem examination that refers to the diagnosis “death by lightning” is bleeding from the ear canal following a ruptured tympanic membrane from the barotrauma associated with the lightning strike [20,21,22]. This injury may occur on one or both sides whereas ruptures of both tympanic membranes are described less frequently. There are different statements in the specialist literature about the frequency of occurrence of tympanic membrane ruptures in relation with an accident caused by lightning. These range from 10% (examination collective with n = 5) over 50% (n = 66) to over 80% (n = 45) [16, 23, 24].

Bleeding from the ear canal in an unobserved accident caused by lightning is rarely sufficient as a diagnostic finding, since there are numerous other causes of bleeding from the ear canal, such as skull base fractures, brain tumors, ear furuncles, or foreign objects. In observed events, on the other hand, in addition to a rupture of the tympanic membrane, a basal skull fracture after a serious fall must also be considered. Cherington et al. reported a case in which bilateral tympanic membrane ruptures combined with thermal damage of a worn jogging shoe were the only findings in an unobserved death from lightning strike [21].

Metallization effects on the skin are relatively rare and have never been the sole finding that led to the diagnosis of “death by lightning” in cases published to date [10, 25].

Doctors performing the external postmortem examination who are not sure whether a lightning strike caused injuries have been able to get support of regional lightning detection systems for many years. If one is interested, any doctor and any other person can research whether cloud-to-earth lightnings have been registered for an explicit time and location. So far, this service has helped to classify unexplained deaths correctly and to provide scientific research with specific data on the times, locations, and amperages of the detected lightning strikes [22, 24, 26,27,28]. For example, with the help of the US National Lightning Detection Network (NLDN) (Table 4), it was demonstrated that a cyclist’s acute cardiac arrest, which occurred under cloudless skies, was due to a lightning strike occurring 10 miles (16 km) from the associated thunderstorm cell (“bolt from the blue”) [11].