Before looking up the proper statutes, I need to observe that Strange Case of Dr Jekyll and Mr Hyde was written in 1886. While technically set in London, and to apply civil law, I will replace all instances of London with Berlin, so that we can apply the Prussian laws. In 1886, that would be the Preußisches Strafgesetzbuch 1851, § 175 to §177:
§ 175 [Mord] Wer vorsätzlich und mit Ueberlegung einen Menschen
tödtet, begeht einen Mord, und wird mit dem Tode bestraft. [inapplicable]
§ 176 [Totschlag] Wer vorsätzlich, jedoch nicht mit Ueberlegung, einen Menschen tödtet, begeht einen Todtschlag, und soll mit lebenslänglichem Zuchthaus bestraft werden.
§ 177 [Totschlag im Affekt] War der Todtschläger ohne eigene
Schuld durch eine ihm selbst oder seinen Angehörigen zugefügte Miß-
handlung oder schwere Beleidigung von dem Getödteten zum Zorne
gereizt und dadurch auf der Stelle zur That hingerissen worden, so
bleibt die lebenslängliche Zuchthausstrafe ausgeschlossen, und es soll
auf Gefängniß nicht unter zwei Jahren erkannt werden.
These are three different types of murder: preplanned, deliberate killing is Mord under 175, killing deliberately but without planning is Totschlag (manslaughter) under 176, and a killing without deliberation or planning is Totschlag im Affekt (manslaughter in the heat of passion). So there are three degrees that can be applied, and we need to see the situation that led to the killing.
Then, we need to see what the Insanity defense is then:
§ 40 [Unzurechnungsfähigkeit] Ein Verbrechen oder Vergehen ist
nicht vorhanden, wenn der Thäter zur Zeit der That wahnsinnig oder
blödsinnig, oder die freie Willensbestimmung desselben durch Gewalt
oder durch Drohungen ausgeschlossen war.
Please open your textbook to the following chapter and read the first paragraph to get the description of the situation that led to the killing, with special emphasis on the section embolded:
The Carew Murder Case
Nearly a year later, in the month of October, 18—, London was startled by a crime of singular ferocity and rendered all the more notable by the high position of the victim. The details were few and startling. A maid servant living alone in a house not far from the river, had gone upstairs to bed about eleven. Although a fog rolled over the city in the small hours, the early part of the night was cloudless, and the lane, which the maid’s window overlooked, was brilliantly lit by the full moon. It seems she was romantically given, for she sat down upon her box, which stood immediately under the window, and fell into a dream of musing. Never (she used to say, with streaming tears, when she narrated that experience), never had she felt more at peace with all men or thought more kindly of the world. And as she so sat she became aware of an aged beautiful gentleman with white hair, drawing near along the lane; and advancing to meet him, another and very small gentleman, to whom at first she paid less attention. When they had come within speech (which was just under the maid’s eyes) the older man bowed and accosted the other with a very pretty manner of politeness. It did not seem as if the subject of his address were of great importance; indeed, from his pointing, it sometimes appeared as if he were only inquiring his way; but the moon shone on his face as he spoke, and the girl was pleased to watch it, it seemed to breathe such an innocent and old-world kindness of disposition, yet with something high too, as of a well-founded self-content. Presently her eye wandered to the other, and she was surprised to recognise in him a certain Mr. Hyde, who had once visited her master and for whom she had conceived a dislike. He had in his hand a heavy cane, with which he was trifling; but he answered never a word, and seemed to listen with an ill-contained impatience. And then all of a sudden he broke out in a great flame of anger, stamping with his foot, brandishing the cane, and carrying on (as the maid described it) like a madman. The old gentleman took a step back, with the air of one very much surprised and a trifle hurt; and at that Mr. Hyde broke out of all bounds and clubbed him to the earth. And next moment, with ape-like fury, he was trampling his victim under foot and hailing down a storm of blows, under which the bones were audibly shattered and the body jumped upon the roadway. At the horror of these sights and sounds, the maid fainted.
Our report here indicates two things: First, the Maid described the interaction from a distance and could not hear whatever what was said, but from gestures alone, it seemed the victim was decently polite. Second, Mr Hyde was very much agitated throughout the interaction and then, in what appears as a spur-of-the-moment, committed the killing.
As such, it seems very much so that we can not get a conviction for Mord, as Mr Hyde did not pre-plan a killing, either of this specific victim or any at all. However, at some point during the polite talk to him by the victim, he decided to kill the victim, without provocation. As such, the Manslaughter in the Heat of the Passion is not available, and the proper sentence is to lock up Mr. Hyde for life under §176. The insanity defense under §40 requires "Wahnsinn" (madness), "Blödsinn" (mentally incapable) or being incapable to having a free will due to a threat-personality disorder like that of Jackyll and Hyde, would not be considered Wahnsinn, or mental incapacity: both personalities are fully capable, and not incapable. Since neither of the three mitigations is applicable, this leaves us with lifelong imprisonment.
