Looking at several stories on this, it seems that the drone was used to aid in executing a lawful arrest, not to gather evidence.
The exact timeline is unclear, but many of the stories indicate that the drone was brought in after the arrest turned into an armed standoff, with the drone being used to figure out where the armed people were so that the arrests could be made safely.
Under those circumstances, I don't see how using the drone would require a warrant.
The exact timeline is unclear, but many of the stories indicate that the drone was brought in after the arrest turned into an armed standoff, with the drone being used to figure out where the armed people were so that the arrests could be made safely.
Under those circumstances, I don't see how using the drone would require a warrant.