Detective Case Files

Detective Case Files is a quest in Fallout 4.

Quick walkthrough

 * Head to Nick Valentine's Detective Agency.
 * Talk to Ellie Perkins.
 * Accept her request in solving some cases.
 * One will acquire the Earl Sterling Case File and the Marty Bullfinch’s Holotape. Picking up the former will start the side quest "The Disappearing Act", while listening to the latter will start The Gilded Grasshopper.

Detailed walkthrough
You begin the quest by reading the case file on the table. You can optionally ask about Earl Sterling but its not neccessary. When you ask Vadim Bobrov about Earl Sterling, he will give you the keys to his house, letting you look arround. You can find a surgery receipt on the floor, next to the sofa. This will lead you to the Mega surgery center in Diamond City. Interrogating Dr. Sun, you can ask about the bloodstains on the floor leading to the cellar. If the interrogation is succesfull he will give you the keys to the cellar. Entering the cellar you can see Dr. Crocker speaking with the corpse of Earl Sterling, talking about how he shouldn't bleed during the surgery. Noticing you, Dr. Crocker tells you that surgery went bad that he is high on Jet. You can either choose to kill him, arrest him or let him go, but he will kill himself no matter what, injecting his body with a lethal dose of Psycho. A few seconds after that, Dr. Sun enters the cellar to discover what really happened. You explain to him that the operation went badly and Dr. Crocker wanted to hide the body in the cellar.