Ji Sung's Secret was Already Found Out by Another Detective in Connection Episode 11

In episode 11, the identity of the 'doctor' was known because Gong Jin Wook contacted him to ask for help to flee the country to China to sell the Lemon Mulberry. After the death of CEO Yoon, no client wants to buy and sell any longer. In here, the identity of Sang Eui as the doctor became known to us viewers. 

Jin Wook, handed over 2 valuable things to him. Jae Gyeong's gun as well as a USB which we don't know yet what it contains. Although I have an assumption that a video of Jae Gyeong getting drugged was in there. I'm hella scared for Jae Gyeong now, tbh. Detective Kyung Hwan, who's in contact with Tae Jin, also found out about him being drugged already via another arrested addict, Dae Sung. A little time is left for our protagonist, Jae Gyeong now! Waa!

Now lets go back with Sang Eui being the 'doctor'. Tbh, now that I saw everything, anyone in Jong Soo's group can become the 'doctor'. Jong Soo's group is the manufacturer and the dealer of Lemon Mulberry and since everyone in the group functions as one, the doctor can be anyone when the other is unavailable. In the previous episode, Gong Jin Wook mentioned that the voice of the 'doctor' that he's talking with over the phone was different from the last call he had received. I assume it was Jun Seo dealing with him at that time, but since Jun Seo is now dead, it's Sang Eui the researcher who became the doctor. 

However, I think that, Jong Soo and Chi Hyun are unaware of the shared account of Tae Jin and Jun Seo. According to Jae Gyeong, the said account may contain the money from selling Lemon Mulberry. The reason why Tae Jin is so confident in becoming an investor for the Pilo-dong project is that he has that account that contains a lot of money. Since Jong Soo didn't know about it, I have assumed that Tae Jin has other transactions dealing with the Lemon Mulberry that only Jun Seo and Sang Eui knew about. Hmmm... this is getting complicated but really exciting on who's the one who really killed Jun Seo. 

Sang Eui seems to be living a 2 faced life. One who's taking orders like a pushover from Jong Soo's group and one who's having plans of his own. Sang Eui is backstabbing the group for sure. He gave a recording of the group's meeting, where they thought about eliminating Yoon Ho, to Yoon Ho himself. And that's how Yoon Ho had known from Sang Eui also that Tae Jin is in accomplice with Ji Yeon in killing Jun Seo... that Ji Yeon has the evidence in killing him. Sheesh...