Dumbledore did it, but he did not do it personally.
If Dumbledore manipulated Bones into murdering Narcissa, then we would have a universe where both Dumbledore and Bones would be emotionally affected by her death, where Bones would not want Dumbledore to take the legal blame and where Dumbledore would willingly take the (informal) blame.
I don’t think Amelia Bones is the kind of woman who needs to be manipulated by Dumbledore to get revenge. My similar hypothesis is that Amelia needed Dumbledore’s help to infiltrate Malfoy Manor and pull it off. Aberforth’s death provided the impetus for Dumbledore to help, but he didn’t cast the spell.
There is, of course, the Third Option.
Dumbledore did it, but he did not do it personally.
If Dumbledore manipulated Bones into murdering Narcissa, then we would have a universe where both Dumbledore and Bones would be emotionally affected by her death, where Bones would not want Dumbledore to take the legal blame and where Dumbledore would willingly take the (informal) blame.
I don’t think Amelia Bones is the kind of woman who needs to be manipulated by Dumbledore to get revenge. My similar hypothesis is that Amelia needed Dumbledore’s help to infiltrate Malfoy Manor and pull it off. Aberforth’s death provided the impetus for Dumbledore to help, but he didn’t cast the spell.