Hi,
"The killer left a string of pulverized corpses behind him"
why would the sentence use "pulverized" instead of "pulverizable"
pulverized - describes the corpses, ie the killer actually did this.
pulverizable - the ending -able indicates the corpses were capable of being pulverized, ie it was a possibility. This does not explicitly tell us whether the killer actually did it.
It's pretty odd to say 'pulverizable'.
A more normal example is this.
a painted surface - someone has painted it.
a paintable surface - you can paint it if you want to.
Best wishes, Clive