if you want to understand the artist, look at his work. ... The successful serial killers plan their work as carefully as a painter plans a canvas. They consider what they do their “art,” and they keep refining it as they go along.
Douglas, John E., Mindhunter, (1996, p. 116).

Insane minds think alike

Writing to his devoted follower, Princess Marie Bonaparte, on August 13, 1937, almost exactly two years before his death, Freud revealed his life philosophy stating:
The moment a man questions the meaning and value of life he is sick since objectively neither has any existence. *

What may not be apparent at first sight is the fact that this is the motivation of a murderer. If a life has no meaning or value, taking someone else's life is inconsequential.
This is an odd statement taking into account that Freud was afraid of death. He didn't mean of course that his life was without meaning or value. On the contrary, Freud's own life had meaning and value for Freud, it was other people's lives that for Freud had no meaning and value. A motivation, as good as any, for a serial killer.
* Freud, Sigmund, Letters of Sigmund Freud 1873-1939, (1960, p 436).

In a letter to his biographer and psychoanalyst, Franz Wittels, of December 18, 1923, Freud stated:
It seems to me that the world has no claim on my person and that it will learn nothing from me so long as my case (for manifold reasons) cannot be made fully transparent.*
* Freud, Sigmund, The Letters of Sigmund Freud, (1960, p. 346).

Now, what kind of (mental) case was Freud, and what were the manifold reasons why the truth could not be told?
Without a doubt, Freud was hiding ugly secrets that couldn't see the light of day.

Destroy the whole world

In the letter of August 15, 1877 to his friend, Eduard Silberstein, Freud aged 21, revealed what was on his mind writing, I wish for all the rabble found on this earth to be struck down by heavenly thunder and the world to become so depopulated that one would encounter just one human being every three miles.
Freud didn't have much sympathy for the humankind.
If this wish remains unfulfilled, he threatened, posterity will rue the day. A certain number of scoundrels is quite acceptable, he explained, but too many are unhealthy. (1)
Without a doubt, these weren't musings of a sane person but rather of a murderous psychopath.
On another occasion, writing to his fiancé on June 24 (?), 1883, Freud, aged 26, in no uncertain terms, revealed what was on his jealous mind.
When memory of your letter to Fritz (his fiancé’s unsuccessful beau) ... comes back to me I lose all control of myself, and had I the power to destroy the whole world, ourselves included, to let it start all over again - even at the risk it might not create Martha and myself - I would do so without hesitation.
Apparently, on this particular occasion, Freud contemplated not only mass killing but also murder-suicide.
Also, Charles Starkweather hated the world he happened to be born into. I wanted in general revenge upon the world and its human race, my mind and heart became black with hatred, (3)  he explained.  And he added that he was mad at the world. (4)
Just like Freud, Starkweather hated the whole of humanity. Sometimes I thought about murdering the whole human race, he confessed  (5)
(1) Freud, Sigmund, The Letters of Sigmund Freud to Eduard Silberstein, 1871-1881. (1991, p. 164).
(2) Jones, Ernest, Sigmund Freud: Life and Work: Years of Maturity, (1953, pp. 114-115).
(3) Leyton, Elliott, Hunting humans : the rise of the modern multiple murderer, (2003, p. 293).
(4) Leyton, (2003, p. 297).
(5) Leyton, (2003, p. 300).

Freud wasn't hiding his psychopathology from his followers. This is how he explained his life philosophy to the Swiss pastor, Oscar Pfister, on October 9, 1918:
ethics are remote from me … I do not break my head very much about good and evil, but I have found little that is "good" about human beings on the whole. In my experience most of them are trash …
Freud, Sigmund & Pfister, Oscar, Psychoanalysis and Faith: The Letters of Sigmund Freud and Oskar Pfister, (1963, p. 61).

Reading murder mysteries

Reading the available literature on the subject is the best way how to learn to commit a perfect crime, as Freud did. No wonder that Freud, indulged his taste for murder mysteries by such classic detective story writers as Agatha Christie and Dorothy Sayers. (1)
Also, Paula Fichtl, (1902-1989), Freud’s housekeeper for many years, observed that, he was almost always reading a Sherlock Holmes mystery. For crime novels, Freud mostly chose English authors such as G. K. Chesterton, Agatha Christie and Dorothy Sayers. Interestingly, the professor almost always knew who the killer was but when it turned out to be someone else, he got angry. … The detective stories were always there on his bedside table. (2)
Undeniably, Freud's strategy worked since he was never caught, and never brought to justice, even worse, hailed as a genius, Freud died in the safety of London, in his own bed.
Freud's interest in criminal stories is mirrored by other serial killers. Thus, in the possessions of sexually sadistic serial killers we find that many of them have collections of detective magazines.  (3)
Ted Bundy also confessed to being an avid reader of pulp detective magazines, of the type that [other killers like] Ed Gein, John Joubert, and Harvey Glatman were reading. Bundy... was also getting an education in police procedures and crime techniques = what worked and what did not. (4)
(1) Gay, Peter, Freud: A Life for Our Time, (1988, p. 266).

(2) Berthelsen, Detlef, Alltag bei Familie Freud: Die Erinnerungen der Paula Fichtl, (1989, p. 33). [Author’s translation].
(3) Tithecott, Richard, Of Men and Monsters: Jeffrey Dahmer and the Construction of the Serial Killer, (1998, p. 115).

(4) Vronsky, Peter, Serial Killers: The Method and Madness of Monsters, (2004, p. 111).

 A legitimate cause of death

Ten, maybe more, of the 149 psychoanalysts of the Viennese Psychoanalytic Association - Freud's infamous creation - died - allegedly having committed suicide.
How many of them died by their own hand, and how many Freud sent to the happy Viennese hunting grounds, is an open question. Most certainly more than a few.
Being Freud's follower was risky business, especially if you disagreed with the "great" man,
Unsurprisingly, like most serial killers,Freud enjoyed writing about his lethal "successes". Thus, in the letter to Jung, on April 2, 1911,  referring to the death of their disciples, Freud wrote, Do you know, I think we wear out quite a few men. (1) Freud, most certainly did, and he wasn't sorry about it. Was he, as it appears, in this way intimating that also Jung was killing his fellow psychoanalysts? Maybe he did.
One of Freud's mental patients from America -  most of them came from the States - Abram Kardiner - who pilgrimaged to Vienna to be saved by the prophet - In his recollections of his analysis with Freud recalled that on one occasion he had the opportunity to find out Freud's views about his followers' death.
I once discussed with Freud the suicides of two analysts in Vienna, he recalled. His eyes twinkling, he commented, ‘Well, the day will come when psychoanalysis will be considered a legitimate cause of death." (2)
Of course, neither Kardiner, nor anyone else, so far, had any idea what the serial killer, Freud, was hinting at. Without a doubt, as it is not uncommon with serial killers, Freud was enjoying this moment.
As Roazen pointed out, The impersonal-sounding word "psychoanalysis" in fact, at the time, meant Freud personally. (3) And since Freud in his own mind was psychoanalysis, the statement gets an even more ominous meaning, Well, the day will come when Freud will be considered a legitimate cause of death.
Whose deaths did Kardiner discuss with Freud? Since, as he recounted, Kardinerwas in Vienna in the years 1921-1922, it appears that one of the two analysts' deaths, Kardiner was discussing with Freud, was the case of Tausk who died in 1919.
No wonder that having gotten rid of his rival, Freud was revelling in Tausk's death.
(1) Jung, Carl G. & Freud, Sigmund, The Freud/Jung Letters: The Correspondence Between Sigmund Freud and C. G. Jung, (1974, P. 413).
(2) Kardiner, Abram, My Analysis with Freud: Reminiscences, (1977, p. 70).
(3) Roazen, Brother Animal: The story of Freud and Tausk, (1969, p. 25).

The Future of an Illusion

When people read Freud, they assume they are reading fiction. Nothing could be further from the truth. Freud's writings are autobiographical, a reflection of his deranged personality. When Freud talks about issues, he means what he says. Oddly, almost no one took him seriously when he was describing his perversions and criminality.
This is what he revealed about himself, in The Future of An Illusion, of 1927, bizarrely projecting his deranged ideas on the whole of humanity.
The instinctual wishes that suffer under [privations of civilization] are born afresh with every child; there is a class of people, the neurotics, who already react to these frustrations with asocial behaviour. Among these instinctual wishes are those of incest, cannibalism and lust for killing. (1)
Let's analyse what Freud was saying: The problem is that the civilisation doesn't allow its citizens to fulfil their instinctual wishes". As he clarified, those wishes are, incest, cannibalism and lust for killing. And he explained that as a result of those, privations, the neurotics ... react to these frustrations with asocial behaviour.
Keeping in mind that Freud described himself as a neurotic, this is Freud's explanation for his asocial behaviour. Considering himself a Superman, and thus entitled to making his own rules, Freud lived as he preached, practising, incest, cannibalism and ... killing.
Notably, Freud pointed out that, cannibalism,  but only, to the non-psycho-analytic view, seems, to have been completely surmounted. What is he saying?
Since Freud, as he claimed, as its creator, was identifying himself with psychoanalysis, the claim is chilling. Thus, Freud the neurotic was exempt from the prohibition of cannibalism. Likewise, Freud's statement regarding, the strength of the incestuous wishes, is a direct hint that Freud didn't overcome these wishes practising them in his own home with his daughters and sons. As he also pointed out, under certain conditions killing is still practised ...by our civilization. (2) Notably, Freud didn't mention which conditions allowed him, as a neurotic, to kill.

Civilization and Its Discontents

Further only three years later, in Civilization and Its Discontents, of 1930, projecting his deranged personality on humankind,  Freud explained that in his view, men are not gentle creatures who want to be loved. As he saw it, their neighbor is for them ... someone who tempts them, to use him sexually without his consent, to seize his possessions, to humiliate him, to cause him pain, to torture and to kill him. (3)
Even though there may be a seed of truth in Freud's claim about men not being gentle creatures, the totality of his claim is absurd, applying only to Freud himself. As a matter of course, if he were right, we wouldn't be able to function as a society. There's no doubt that some people, only a minority, under special circumstances, will steal, attack, even torture and kill, but this is not a rule, but rather an exception. Even though all of us have a capacity for all those things, very few of us torture and kill.
Under normal circumstances, a person realises that there's a limit to what is permissible. The case is, of course, different when we have to do with "neurotics" like Freud. Insanity and psychopathy, as evidenced by Freud's evil deeds, create its own rules
(1) SE 21, p. 10.
(2) SE 21, p. 11.
(3) SE 21, pp. 111 

Serial killer Doctor Freud

Why did Freud choose to become a doctor rather than a lawyer, which he initially intended? The answer is obvious: to have easy access to his, in the first place, female victims whom he could exploit sexually without risking ever being locked up as a pervert and rapist. Moreover, in his profession, he was immune from prosecution. A doctor, during Freud's time, had, in principle, a license to kill. And Freud was not only killing patients, some due to his incompetence, some for fun; he was also killing his family members, disciples, and strangers.
When discussing Freud's criminality, It is worth keeping in mind that,
While every serial killer is mentally disordered, nearly all are psychopathic sexual sadists. ... Like other sexual sadists, they [serial killers] often pursue occupations and hobbies that bring them in contact with injured and suffering people or people over whom they have control.
Ambulance services, hospitals, mortuaries, ... prove attractive to them. *
These men enjoy killing people. **
This statement clearly explains Freud's choice of profession, and his fascination with death.
A case in point: As a doctor in private practice, Freud had free and unsupervised access to unsuspecting women, exploiting sexually most of them, raping some, and killing a select few.
Killing females was for Freud a secondary thing. Freud hated men more, and, consequently, Freud was mostly killing men.

* Dietz, Park Elliott, Mass, Serial and Sensational Homicides, Bulletin of the New York Academy of Medicine, Vol. 62, No. 5, (June 1986, p. 483).
** Dietz, (1986, p. 487).

Hater

This is how, in The Interpretation of Dreams, (1900) which contains lots of his intimate confessions, Freud, aged 44, explained his hatred by example:
            There is a person of my acquaintance whom I hate, that I have a lively inclination to feel glad if anything goes wrong with him. ...  my satisfaction seems more intense than that of these other people; it has received an accession from the source of my hatred. (1)
            Freud's maniacal, pathological - more intense than other people’s - hatred was, definitely, not, what one would consider, normal. Interestingly, Freud wasn’t hiding his despicable nature from his fiancé, writing in his letter of August 22, 1883: I also have the capacity ... of hating someone on intellectual grounds, just because he is a fool. (2)
Unsurprisingly, Freud's hatred didn't go unnoticed among his followers. Thus, an analyst, interviewed by Roazen, exclaimed of Freud: Oh, how he could hate! The obvious question is, in what way did Freud express his hatred?  (3)
As Freud's former favourite pupil. Theodor Reik explained that Freud was capable of much love, but he was also a good hater. (4) Freud capable of love? No one else said that about Freud - but without a doubt, Freud was a pathological hater.

Sadistic hater 

This is how, yet another of Freud’s longtime followers, Isidor Sadger, recalled the inner workings of Freud’s psyche: Sigmund Freud was always an extreme hater. That he was always able to hate by far more than he could love is connected to his strong sadistic disposition. (5)
      So, not only was Freud a pathological hater, he was also a sadistic one. This is an important piece of information about Freud’s character since, as a forensic psychiatrist, Park Dietz pointed out:
            While every serial killer is mentally disordered, nearly all are psychopathic sexual sadists, and few, if any, are psychotic. Psychotic offenders rarely have the wherewithal repeatedly to escape apprehension. (6)
Since Freud was able to avoid being apprehended, it is obvious that Freud was not psychotic, just insane. And the fact that he was a (sexual) sadist, according to Sadger, fits nicely in Freud’s profile as a serial murderer.

Freud's hate list

In July 1931 Freud informed one of his followers, Max Eitingon, that in his leisure time he had composed what he called a "hate list” of seven or eight people. (7)
A hate list, or the murder list, that is the question. Most probably the list was a permanent thing, the names of the list changing from time to time, keeping pace with the number of suicides among Freud's disciples. Notably, even though Freud had only eight more years to live, he was still obsessing about his enemies, no doubt, the people whom he would happily murder if having an opportunity to do so.

Murderous hatred of the father

Freud’s capacity for hatred wasn’t acquired, rather it was part of his character, also obvious in his childhood. Thus, reflecting on his hateful attitude towards his father, in The Interpretation of Dreams, Freud claimed that, It is the fate of all of us, perhaps, to direct our first sexual impulse towards our mother and our first hatred and murderous wish against our father. Of course, Freud's insane ideas applied only to him. Most certainly, they couldn't be generalised to the whole world's male population. After all, incest with the mother and murder of a father is a rare occurrence.

Mighty passions

Notably, Jones pointed out, how mighty were the passions that animated Freud and how unlike he was in reality to the calm scientist he is often depicted. He was beyond doubt someone whose instincts were far more powerful than the average man's, but whose repressions were even more potent, as is not unusual in the criminally insane.
It is an important revelation. Thus, on one hand, Freud was governed by mighty passions, on the other hand, he was able to hide them from the people he was engaging with. How did he do it?

Freud's hypocrisy

Recounting his strategy in his daily life, Freud pointed out the fact that, The suppression and inversion of affects is useful even in social life, as is shown by … above all, hypocrisy. And Freud should have known what he was talking about being the master of the latter. This is how he explained his actions:
If I am conversing with a person to whom I must show consideration while I should like to address him as an enemy, it is almost more important that I should conceal the expression of my affect from him than that I should modify the verbal expression of my thoughts. (9)
This is how Freud explained his approach:
If I address him in courteous terms, but accompany them by looks or gestures of hatred and disdain, the effect which I produce upon him is not very different from what it would have been had I cast my unmitigated contempt into his face. Above all, then, the censorship bids me suppress my affects, and if I am a master of the art of dissimulation I can hypocritically display the opposite affect - smiling where I should like to be angry, and pretending affection where I should like to destroy. (10)
In particular, as Freud explained, this kind of strategy is being used, where two persons are concerned, one of whom possesses a certain degree of power which the second is obliged to take into account. In such a case the second person will distort his psychical acts or, as we might put it, will dissimulate. One of those persons, he talks about, was Freud. This is how he explained his actions: The politeness which I practise every day is to a large extent dissimulation of this kind. (11)
Most certainly, Freud was a master of dissimulation. No wonder, his victims had no idea about the degree of Freud’s lethal hatred towards them, paying with their lives as a consequence of their blindness.

Freud the murderous dreamer

In A general introduction to psychoanalysis (1920), Freud clearly explained what went on in his insane mind, stating that,
Revenge and murderous wishes toward those standing closest to the dreamer are not unusual, toward those best beloveds in daily life, toward parents, brothers and sisters, toward one's spouse and one's own children. (12)  And, as a means of normalising the abnormal, Freud claimed that,
all people have such perverse, incestuous and murderous dreams, and not the neurotics alone. (13)
Of course, being himself a neurotic, and only dealing with hysterical patients, a good question is how Freud could have known what normal dreams are like.
Freud further explained that, in our unconscious we daily and hourly do away with all those who stand in our way, all those who have insulted or harmed us. (14)
Murder was a subject occupying Freud, and, terrifyingly, not only in his dreams. Could Freud say it more openly without incriminating oneself? There’s a valid question: how could Freud know what goes on in one’s unconscious which we, by definition, aren’t conscious about? Without a doubt, t least in Freud’s case, the murderous ideas weren’t unconscious.
If it notable that Freud, who revealed his dreams in his dream book, in his Some Additional Notes On Dream Interpretation As A Whole (1925), claimed that, one must hold oneself responsible for the evil impulses of one’s dreams. ... Unless the content of the dream ... is inspired by alien spirits, it is a part of my own being. (15)
One can only agree. Assuming Freud's dreams weren't inspired by alien spirits - not likely - they were a part of Freud's murderous being. What is worse than his dreams, of course, and more important, are Freud’s actions when he was awake. Contradictory to his symbolism as presented in his dream book, Freud claimed that the majority [of dreams] really mean what they say ... They are an expression of immoral, incestuous and perverse impulses or of murderous and sadistic lusts. (16)
Keeping in mind that, in the dream book, Freud revealed his, own dreams, it is apparent that his "dreams" are nothing else but a mirror image of his own round-the-clock insane personality.
(1) SE 5, pp. 478-479.
(2) Freud, Sigmund, The Letters of Sigmund Freud, (1960, p. 43).
(3) Roazen, Paul, Freud and His Followers, (1975, p. xxvi).
(4) Reik, Theodor, From thirty years with Freud, (1940, p. 6).
(5) Sadger, Isidor, Recollecting Freud,(2005, p. 105).
(6) Dietz, Park Elliott, Mass, Serial and Sensational Homicides, Bulletin of the New York Academy of Medicine, Vol. 62, No. 5, (June 1986, p. 483).
(7) Jones, Ernest, Life and Work of Sigmund Freud: The Last Phase, (1957, p.159).
(8) Jones, Ernest, Life and Work of Sigmund Freud: The Formative Years and the Great Discoveries, (1953, p. 138).
(9) Freud, Sigmund, The Interpretation of Dreams, (1913, p. 375).
(10) Freud, (1913, p. 334).
(11) SE 4, pp. 141-142,
(12) Freud, Sigmund, A General Introduction to Psychoanalysis, (1920 p. 116).
(13) Freud, (1920, p. 203).
(14)  Freud, Sigmund, Reflections on War and Death, (1918).
(15) SE 18, p. 133).
(15) SE 18, p. 132).