An easy way to get this (or finish it up) is in a small semi-sunken room in the Triton Theater area of Dionysus Park. On your map of Triton Theater, this room is straight north of the healing station furthest left. You have to hack a door to get in, and there's a safe in there. Keep tripping the alarm on the safe to bring in security bots. Hack a couple then take cover in the corner by the door and let them kill every bot that comes through. When they go down, hack two more, etc. until done. What's so nice here is that if you have Fountain of Youth equipped, you'll just stand there knee-deep in water and heal while your hacked bots do all the work. I never fired a shot to be certain my bots were getting the kills.