Help. BL webtoon murderer and pretendstalker

Help find BL webtoon
The MC accidentally witnesses a murder and in panic, told the murderer that he likes him (and that he is a stalker?)
The murderer is actually a hitman I believe, and works as a veterinarian. (He also has a sister who is in the same business?) Very handsome
So basically MC pretends to be madly in love in order to stay alive.

Please help. I've been searching this for weeks