Ryan Andrews is found during the Haworth Labs mission. After getting your press pass and entering HL, you will have to make your way through some levels and finally make it to a bobby sitting at a desk. He will say you're not allowed and message Verloc who says your an imposter and the bobby will attack you. After defeating him, you need to make your way up the flight of stairs. Ryan was on the left side near a switch for me. I personally choked him out, then hit him with a hammer. Be careful though, there is scientists everywhere in here.
Happy achievement hunting! Hope this helps.