Depending on the edition, speak with dead requires the corpse to have a working jaw, so just destroy that. If you hide the head, someone can just find it.
A skull is an object(since Mending can repair wine skins, which are made of animal product, it just can't be a living thing), and all the breaks are just breaks. So, you acid off all the nonessential bits, puzzle the skull (or just the mouthy bits) back together and then mend the cracks. Done, a perfectly usable Speak with the Dead target. Would anyone do this in real life? Definitely, since there's so much info you could get. I'd let It play as DM
And if you can't find all the pieces, what then? And even if you did, assuming a human skull is an "object" (which I dispute), there will certainly be more than a single tear or break. So what, is each pair of puzzle pieces now an object you can cast mend on?
I don't think that matches the intention of the spell at all.
Although CSI Faerun would be kinda fun, so maybe I'd allow it.
This is all stuff you'd have a reason to know in character when a setting includes something as impactful as the ability to use the dead as a witness. If the victim can be a witness, you need to either fool or silence the victim post-mortem.
There are many ways to keep a witness from identifying you. You just need to be creative.
Yes DM, this comment right here.
I see you have a lot of experience in the field
I'm writing a murder mystery adventure in my spare time, so… Yeah, it came up.
Depending on the edition, speak with dead requires the corpse to have a working jaw, so just destroy that. If you hide the head, someone can just find it.
Why hide it? A maul is cheap.
Mending
Mending fixes a single tear or break in an object. No way should that work on a head that's been splattered halfway across the Sword Coast.
A skull is an object(since Mending can repair wine skins, which are made of animal product, it just can't be a living thing), and all the breaks are just breaks. So, you acid off all the nonessential bits, puzzle the skull (or just the mouthy bits) back together and then mend the cracks. Done, a perfectly usable Speak with the Dead target. Would anyone do this in real life? Definitely, since there's so much info you could get. I'd let It play as DM
And if you can't find all the pieces, what then? And even if you did, assuming a human skull is an "object" (which I dispute), there will certainly be more than a single tear or break. So what, is each pair of puzzle pieces now an object you can cast mend on?
I don't think that matches the intention of the spell at all.
Although CSI Faerun would be kinda fun, so maybe I'd allow it.
Can't find all the important pieces, it doesn't work, simple as that.
RAW, you can cast mending multiple times on the same object to fix multiple breaks, so that should be fine.
It's got the right level of complete nonsense, excruciating tedium, and hilarious results I love to see at the table.
Can a dead body without a tongue still speak when affected by speak with the dead?
I believe the requirement is jaw not tongue.
This is all stuff you'd have a reason to know in character when a setting includes something as impactful as the ability to use the dead as a witness. If the victim can be a witness, you need to either fool or silence the victim post-mortem.