Resident Evil: The Darkside Chronicles

This is story-related and cannot be missed.

You will earn this in the final Memories of a Lost City chapter (the Resident Evil 2 storyline).
The ‘researcher’ is William Birkin, a worker for Wesker and Umbrella who, as a last resort, uses the virus to mutate, thinking it’ll ‘save’ him. You’ll encounter him before the final chapter, but the trophy only unlocks when you actually kill him.

Anyway, there isn’t much of a strategy. His health drops fast, so all I recommend is shooting and dodging when necessary. Remember to shoot the cable between the cars at the end of the battle when told to, or else Birkin will cover it again, resulting in you having to shoot him for longer (so he can reveal the cables again). This can be deadly if you're low on health/ammo. Once dead, you’ll finish the Memories of a Lost City scenario and earn the trophy.