The killer took off grandpa’s watch? But Jang Gido was wearing it.
At this point I’m thinking the watches we know of aren’t the only ones: victims also had one each, plus grandpa, plus her father. Sibaek’s is his dad’s.
They were given to members of something or on some special occasion. His dad was going to blow the whistle so got killed—thus Sibaek’s quest. Her father maybe abandoned her to protect her? Could have been an illegitimate child since grandma worked for the household—grandpa would be an actual grandpa?
He seemed to be solidly in her camp, so why did he get her arrested? He could have just *not* made her partner. This is weird.