Resident Evil Revelations 2

Quite easy! In Barry's campaign at the point where the game explains stealth kills kill the zombie in front of you and turn right. Do it in the exact order like shown in my video and you can get four at a time. After that quit out to the main menu and restart the process. After five times you got your achievement!
Important is stepping BACK after you kill the second one so you can grab the third one.