Does casting the Detect Evil and Good spell on a killed monster reveal anything?

Question

If I kill some kind of evil creature like a zombie, chuck it into a shallow grave and burn its remains, would casting detect evil and good on the skeletal remains reveal anything?

Or do destroyed/slain monsters immediately stop registering for such effects?

The spell does not specify if the creature needs to be alive, dead, or whole. However, it may cease to be considered a creature if it is dead; I do not know.

The detect evil and good spell description reads:

For the duration, you know if there is an aberration, celestial, elemental, fey, fiend, or undead within 30 feet of you, as well as where the creature is located. Similarly, you know if there is a place or object within 30 feet of you that has been magically consecrated or desecrated.

Additionally, would you know that it was undead? Or just that it is one of those types of monster?

Also, does it remain 'undead'? Once undead, always undead?

I assume this spell only reveals if the monster is one of the types in the list (not which one?), and not alignment like I think perhaps past editions of D&D have done.

Answer 1

Yes, by all means.

To begin, bear with me, the text from the spell Revivify states..

You touch a creature that has died within the last minute. That creature returns to life with 1 hit point. This spell can’t return to life a creature that has died of old age, nor can it restore any missing body parts.

As we can see, rather explicitly, a dead body is still a creature. If it was not, we wouldn't be able to resurrect our dear comrades in battle.

Moving on, from the entry for Improvised Fighting in the PHB..

Sometimes characters don’t have their Weapons and have to Attack with whatever is at hand. An Improvised Weapon includes any object you can wield in one or two hands, such as broken glass, a table leg, a frying pan, a wagon wheel, or a dead Goblin.

And here we can see that clearly, dead creatures are objects.

So, what gives? Simply put, all creatures are creatures, be they alive or dead. However, a creature is only an object if it dies/is dead. Should it return to life, it is no longer an object. But dying does not erase the fact that it is a creature.

Note: Answer is heavily edited, and complete goes against my previous answer. I genuinely apologize to anyone I have misled, but I truly believe this to be the "correct" ruling, at least by RAW.

Answer 2

As a preface, I'm a huge advocate of DM freedom when making a ruling. My initial answer is mold the rules to what your campaign requires. However, from purely a logistical standpoint, I submit the following:

The spell is available to clerics and paladins. This means there is a higher chance of divine intervention when a spell like this is cast. For example, if a dwarven cleric casts this spell on the ashes of a monster that attacked a dwarven citadel, Moradin (the main dwarven deity) will more than likely assist the caster in knowing not only that the monster was evil (or good), but identifying what creature the ashes are from. Please note: this conclusion is not from the actual rule book, just my experience as a DM.

Here is a site that details the spell from 3.5e.

https://www.d20srd.org/srd/spells/detectEvil.htm

In 3.5e, the spell gives more detail the more evil (or good) the target of the spell was. Even though rules from 3.5e don't transfer over to 5e, in this case, they give a good idea of what kind of ruling to make when the details of the rules in 5e aren't specific enough.

With a spell like this, the DM is giving the player the information. The nice part about this is that you have a high degree of freedom to rule in a way that will move the story along in a way that you see fit. When it comes to identifying what kind of creature it was, I would give it to the player if they roll high enough. I don't see a rule that says otherwise, so this is up to DM discretion.

Again, I advocate hugely for DM freedom in ruling. If you are looking for a more rules-based view, Robert Pain VanZant gave a pretty great answer.