What's the plural form of depraved-heart murder? Here's the word you're looking for.
Answer
The noun depraved-heart murder can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be depraved-heart murder.
However, in more specific contexts, the plural form can also be depraved-heart murders e.g. in reference to various types of depraved-heart murders
or a collection of depraved-heart murders.