There is such a thing as perfect murder

Forensic doctor Katharina Feld: Does the perfect murder exist?

This text is part of a series of columns for crime. A lawyer, a prison architect and a forensic doctor report on their daily work, topics that concern them and curious cases.

Many friends and acquaintances ask me the question “Is there such a thing as a perfect murder?” And think: “If someone knows, then she.” And they couldn't be so wrong with that. The definition of murder (§ 211 StGB) is in itself a legal task. The criteria for this are tightly set. The killing can only be interpreted as murder if it is done out of lust for murder, to satisfy the sexual instinct, out of greed or otherwise for low motives, insidious or cruel or by means that are dangerous to the public. In addition, one speaks of murder if the killing is done to make another crime possible or to cover it up. Insidiousness, greed, lust for murder: these are all legal terms. But it quickly becomes clear that the word murder is used in a rather inflationary manner in general.

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That is why we first use the term homicide in forensic medicine when, for example, we are called to a dead body. At this very early stage in the police investigation, in most cases it is not even clear whether it is a murder according to legal criteria or not. In order to classify an act as murder, knowledge of the motive of the perpetrator or of how the act was carried out is necessary.

What does “perfect” actually mean?

Nevertheless: That is certainly a question that is not that easy to answer. What does perfect mean? Does this mean that you are obviously dealing with a murder, but the perpetrator or even the corpse will never be discovered or does it mean that it is never known that someone has been murdered because it looks like that as if he or she fell asleep peacefully? In principle, the concept of the perfect murder is to be seen quite critically, since perfect sounds at first that it would be something positive to kill someone. It is more about the fact that a murder case cannot be investigated for various reasons.

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In the case of many homicides, it is not yet clear at the beginning of the investigation who the perpetrator is. From experience and also from a purely statistical point of view, it is most likely that one has to look for someone who is close or close to the person who was killed. Often there was a family, partnership or friendship relationship before death. Correspondingly, it can be difficult for the criminal police in the investigation if these persons are out of the question as perpetrators, but someone completely stranger. Then it is for the police to determine where the person killed was last and with whom she * he had contact in order to narrow down the group of perpetrators. But these are certainly details that a criminal investigator can explain much better.

Leaving no traces on the corpse is basically possible, but unlikely due to the extremely sensitive methods of forensic molecular genetics.

Katharina Feld

Are there any traces on the corpse?

My job as a forensic doctor in this context is, among other things, securing details on the corpse in a way that preserves evidence. The first forensic evidence at the place where the body was found is carried out by employees of the identification service before we forensic doctors can start our examinations. If necessary, we then secure traces of body orifices, for example if there is a suspicion of a sexual offense. It is important here that we do not accidentally destroy or even lay any traces on the corpse, for example our own DNA. And here would be the first starting point for the perfect murder, namely when the perpetrators manage not to leave any traces on the corpse that allow conclusions to be drawn about them. In principle, this is possible, but unlikely due to the extremely sensitive methods of forensic molecular genetics, as here a small flake of skin is often enough to extract enough DNA for a comparison.

Fell down the stairs

Another variant of how a homicidal offense can go undetected is when injuries are provoked, which classically also occur in other processes, such as accidents. The classic for this are fall events of all kinds, whereby the forensic doctor can distinguish findings, for example through a blow on the head, from findings that arise from a fall. However, the more complex the fall and the injuries, the more difficult it will be for us. In this context, the work of the toxicologists to determine intoxication, for example due to alcohol, is essential. Everyone knows that the tendency to fall increases significantly with increasing alcohol consumption.

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It is the same with corpses that are laid on railroad tracks after a killing in order to cover up the killing. Here, too, rolling over the track results in such pronounced injuries or destruction of the body that previous acts of violence that led to death are no longer visible or recognizable. It is important here that the criminal police look for clues as to whether it may be a suicide, for example if a suicide note is found. In addition, even in such cases, a toxicological examination can be very informative when it comes to finding out whether it is possibly also an accident.

In forensic medicine, we attach great importance to autopsy of every infant who dies suddenly and without any known previous illnesses.

Katharina Feld

The defenseless victim

On the other hand, killing with few traces also poses a particular challenge. A classic here is killing with a soft covering (for example a pillow), whereby one usually has no externally visible findings or findings that are easily overlooked. The prerequisite is that the person to be killed is defenseless, for example an infant, a bedridden elderly person or is under the influence of drugs / alcohol. Only then can it be ruled out from the perspective of the perpetrator that there are externally visible injuries that can be traced back to someone defending themselves and which could arouse the suspicion that something is wrong.

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Otherwise there are of course forensic medical methods and methods of securing evidence that can uncover such a homicide. For example, there may be internal injuries that cannot be seen from the outside. For this reason, too, we in forensic medicine, for example, attach great importance to autopsy of every infant who dies suddenly and without known previous illnesses.

This is more difficult for older people with known previous illnesses, since a serious mistake can already occur in the first step of an investigation into the death of a person. In such cases, especially if the person dies at home or in the home, the treating GPs fill out the death certificates. Especially when there are no obvious traces of violence on the corpse, a natural death is generously certified. Since this does not result in a death investigation by the criminal police, of course no one can say whether the deceased may have been the victim of a homicide after all. This point is very important when looking at deaths as a whole. Indeed, not every case is thoroughly investigated. The number of undetected homicides can be correspondingly high.


Killing by poison can only be recognized from the outside by very unspecific findings, for example by a foam mushroom in front of the mouth, whereby in such cases the question arises as to whether the poison may not have been ingested with suicidal intent. It is also seldom possible to administer poison or deadly substances without resistance, unless the victim does not notice that he or she has been poisoned. Thus, different demands are to be made of a murder poison. It should be odorless and tasteless if you want to mix it with food or a drink, ideally lead to symptoms or death with a slight delay and ideally no longer be detectable postmortem. There are certainly better and less well-suited or accessible candidates, but there are also possibilities to use very sensitive toxicological methods to prove the administration of exogenous substances.

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Murder without a corpse is an absolute special case. Such cases occasionally haunt the media and often end in spectacular and media-inflated court cases in which the suspect remains silent about the whereabouts of the corpse. But how does a murder without a corpse come about? Quite simply by having the perpetrator disappear into the corpse. This is possible, for example, by laying the corpse away from the place where it was found (so-called dumping), especially in flowing water, often with previous dismemberment. It is also possible to hide it, for example wrapped in foil and walled in, or make it disappear completely by dissolving it in acid.

So the clear answer to the question of whether there is a perfect murder is: “Yes and no”. Without suspicion that someone might have been killed, it is entirely possible that murder will go undetected. On the other hand, in the event of suspicion, due to the very detailed and precise investigations by the criminal police, forensics, forensic medicine, toxicology and forensic molecular genetics, it is very unlikely that murder and murderer will go undetected. Accordingly, I cannot report a perfect murder, because then it would probably not be a perfect murder.

Would you like to find out more about the work of forensic doctor Katharina Feld? On April 20th at 6 p.m. you will have the opportunity to talk to you and our crime author Manuel Bogner in the crime video chat. Anyone who has completed our polyamory package can take part. You can find out more about it here.