Is murder a necessity to detach your soul?

Question

I want my question to be very specific, so I am starting with some facts:

FACT 1: The process of creating a Horcrux:

The specific processes involved are known to involve a spell and a very horrible act. To split one's soul, one must also commit the most supreme act of evil — murder — and then encase a portion of their fractured soul into a chosen object with an as-of-yet unrevealed spell. Horcrux Wiki

FACT 2: Committing murder makes the soul unstable and full of weak spots

Harry is not a Horcrux. No 'Horcrux making spell' was cast. But he still carries a portion of Voldemort's soul. And that happened too without any killing (murder). This is clear from the Anthony's block quote that states that Voldemort's soul was split at the time of backfiring of the curse and not at the time of killing of James and Lilly.

he had destabilized his soul so much that it split when he was hit by the backfiring curse

• Does a person know when his soul splits?
• Is murder really a necessity to detach one's soul?

Answer 1

It seems pretty well established in the books that splitting your soul requires murder (the supreme act of evil). I also don't think it's correct to say that there was no murder involved when the portion of Voldemort's soul attached itself to Harry. He had, after all, only just murdered both of Harry's parents. That's two acts of murder within a very short period prior to failing to kill Harry, and he had no doubt killed plenty of people without creating Horcruxes before then as well.

JKR: here is the thing: for convenience, I had Dumbledore say to Harry, "You were the Horcrux he never meant to make," but I think, by definition, a Horcrux has to be made intentionally. So because Voldemort never went through the grotesque process that I imagine creates a Horcrux with Harry, (SU: Mm-hm.) it was just that he had destabilized his soul so much that it split when he was hit by the backfiring curse. And so this part of it flies off, and attaches to the only living thing in the room. A part of it flees in the very-close-to-death limbo state that Voldemort then goes on and exists in. I suppose it's very close to being a Horcrux, but Harry did not become an evil object. He didn't have curses upon him that the other Horcruxes had. He himself was not contaminated by carrying this bit of parasitic soul.
_{The Leaky Cauldron, Transcript of Part 1 of PotterCast’s JK Rowling Interview}

The specifics aren't known (yet), but I think we can say with a reasonable amount of certainty that every act of murder damages your soul. It may not be split in to two distinct parts yet - the Horcrux spell may do that, allowing you to extract the smaller portion and bind it to an object - but there's damage that has certainly weakened it.

The repeated process of damaging the soul leaves it full of cracks, weak points that simply need a sufficient amount of force to result in the entire thing shattering in to pieces. The rebounding Killing Curse provides that force: Voldemort's body is destroyed entirely, and his soul splits along at least one of those weak points.

Personally I imagine Voldemort, at the point just before trying to kill Harry, like a vase full of marbles. The rigid sides of the vase keep the marbles in place, but you can reach in and take them out individually, and put them elsewhere. However, if you take a hammer and shatter the vase the marbles go everywhere.

So, to sum up, murder is required to split your soul (or at least damage it enough that it can be split), but I don't think that act of murder would need to come immediately before the creation of a Horcrux, or even need to be committed with the intention of creating one.

Answer 2

Murder is needed to split it, a spell typically detaches the piece.

The usual procedure to make a Horcrux is that the wizard who intends to make one first commits a murder, which splits their soul but doesn’t remove the split piece from inside their body. Then, they use a spell to remove the torn piece from inside them and encase it in an object outside their body.

“How do you split your soul?’

‘Well,’ said Slughorn uncomfortably, ‘you must understand that the soul is supposed to remain intact and whole. Splitting it is an act of violation, it is against nature.’

‘But how do you do it?’

‘By an act of evil – the supreme act of evil. By committing murder. Killing rips the soul apart. The wizard intent upon creating a Horcrux would use the damage to his advantage: he would encase the torn portion –”
_{^{- Harry Potter and the Half-Blood Prince, Chapter 23 (Horcruxes)}}

Murder is the only way mentioned to split the soul, there doesn’t seem to be any other way.

The Dark Lord’s soul broke and stuck in Harry from its instability.

The reason that the Dark Lord’s soul broke and a piece stuck in Harry is because when the Killing Curse rebounded and hit him, his soul that was uniquely unstable because he’d made several Horcruxes was fractured, and a piece went to live on in the living soul that was close by at the time.

“Tell him that on the night Lord Voldemort tried to kill him, when Lily cast her own life between them as a shield, the Killing Curse rebounded upon Lord Voldemort, and a fragment of Voldemort’s soul was blasted apart from the whole, and latched itself on to the only living soul left in that collapsing building.”
_{^{- Harry Potter and the Deathly Hallows, Chapter 33 (The Prince’s Tale)}}

The only reason this happened was because the Dark Lord’s soul was already so unstable, and he’d already committed several murders, including of both Harry’s parents.

“You were the seventh Horcrux, Harry, the Horcrux he never meant to make. He had rendered his soul so unstable that it broke apart when he committed those acts of unspeakable evil, the murder of your parents, the attempted killing of a child. But what escaped from that room was even less than he knew. He left more than his body behind. He left part of himself latched to you, the would-be victim who had survived.”
_{^{- Harry Potter and the Deathly Hallows, Chapter 35 (King’s Cross)}}

In that case as well, murder preceded the splitting and breaking off of the soul.