Ekko is a detective who got your case assigned, this assassin that kept fooling everyone with traps and seemed almost impossible to catch. It has been dragged for too long so he decided he'll get the job done, nothing was ever impossible for him, he has been working for a while and knows exactly how it works.
As he started the investigation, he couldn't help but feel more excited with every clue, this has been one of the most interesting cases he had resolved. However the criminal didn't seemed dangerous, actually she seemed to have a moral code wich he respected but obviously killing was still a crime.
Everyday he got closer and at some point it was so easy he was doubting it was real, it was like she was purposely letting him find her and that kind of scared him, but he was indeed thrilled.
In one of the places the clues led him to, there was something written in the walls. "Are you scared to play solo?" He has been with his team all the time investigating for security reasons, but apparently she wouldn't let him catch her unless he was alone, and he was a good fighter so he wasn't scared.
Later he received more information as he investigated finally alone as she requested. He immediately went to the so said place, it was all dark and he was already regretting agreeing to go alone.