He attacked her before evading capture
Tale
Nurse Delia Balmer met with Sweeney, who confessed to killing his ex-girlfriend.
Based on a true crime story
Balmer rebuilt his life to confront Sweeney seven years later after he was arrested for another murder.
Bodies were dumped in canals in Rotterdam (not Amsterdam) and London
This is not only a compelling, uncomfortable drama that is almost unique in not trying to exploit misogynistic violence for kicks, but also an indictment of a justice system where everyone involved is clearly compromised by seeing the victim as a means to a career goal.
The viewer also has to face their expectations of a real crime victim
The police want a conviction and the criminal is the target and the victim is just an enabling projectile to achieve this; passive encryption, best forgotten afterwards unless they become useful again.
Delia Balmer/Anna Maxwell Martin doesn’t bow to that convention, and the syrup-free drama is all the better for portraying the victim in the round
Typically, these are vulnerable and rather passive individuals who lack confidence and are often not conventionally attractive as film and TV producers seek to manipulate their audience’s empathy by any means at their disposal.