*Note - some achievements don't always pop when they should so do yourself a solid and make a save right before the below so you can do a quick reload if it doesn't pop and prevent needing a full fresh playthrough.
At one point in the story (after Nico's scene with Laine and champagne), the screen will fade to black with "A little while later" and you'll be with Nico in her apartment. She'll chat with Ronnie on the phone before sitting in the chair as George comes by. Another fade out with "A long story later" before Senor Marques moseys on in. He'll present a Photograph in which you need to examine the Child, Man, Woman and La Malediccio triggering Marques to present a Medallion. Examining this reveals it is an Ouroboros and some more story flavor.
Afterwards, talk to Nico and mention Medovsky, Thief, Tattoo then Waterloo Motors which Nico will send their number to your phone. Call them up and mention the Helmet and Tattoo to which the employee doesn't know the killer's name but that he has a car registered on Duchy Street. This will send the investigative duo to London and sending an achievement to your card.