Brain Dead

Brain Dead is a murder-mystery quest in the Fallout 4 add-on Far Harbor.

Quick walkthrough
Ezra Parker is the killer. He killed Julianna Riggs and was using a voice modulator to disguise himself as her the whole time! Find Keith's bat in the corner and the can of red paint, talk to all the robots, then accuse Julianna / Ezra and fight him.

Bugs

 * It is possible for Pearl to become stuck at the elevators, without saying the line about them being out of order. Leading her away and letting her return did not fix it - currently it seems loading is the only fix.