Character appearances }
Main •
Jung Jae-young as Baek Beom : A forensic doctor with ten years of experience at the National Forensic Service. Although his skills are recognized, he is eccentric and has a picky personality. •
Jeong Yu-mi as Eun Sol : A rookie prosecutor working in the 8th Eastern District. She was born into a wealthy family and possesses photographic memory. She is bright and warm-hearted, albeit a little clumsy. •
Park Eun-seok as Kang Hyun :An elite prosecutor who is Eun Sol's senior. •
Oh Man-seok as Do Ji-han : A chief prosecutor who newly transfers to the 8th Eastern District replacing Kang Hyun. He is experienced and clever. •
No Min-woo as Jang Chul / Dr. K (season 2) : He is a warm but quiet doctor who works at Hanju Hospital. He has
Dissociative identity disorder (DID). His other identity is called Dr. K.
Supporting People of National Forensic Service (NIS) •
Stephanie Lee as Stella Hwang (season 1) : A researcher and toxicologist at the National Forensic Service. •
Kang Seung-hyun as Sally (season 2) : A new toxicologist at the National Forensic Service who replaced Stella. •
Ko Kyu-pil as Jung Sung-joo : Forensic Investigator • as Han Soo-yeon : Forensic Investigator •
Joo Jin-mo as Park Joong-ho : Director of the National Institute of Forensic Sciences •
Song Young-kyu as Ma No-dam : Director of the Forensic Investigation Division
People of Seoul Eastern District Prosecutors' Office •
Park Jun-gyu as Kang Dong-sik : A sixth-grade civil servant. He used to be a violent crime detective for 15 years. •
Park Hee-jin as Cheon Mi-ho : An administrative assistant of Seoul Eastern District Prosecutors' Office. • as Yang Soo-dong : An Investigator who works with Do Ji-han. •
Ahn Suk-hwan as No Han-shin : Chief Prosecutor of the criminal department of the Seoul Eastern District Prosecutors' Office. •
Kim Ho-jung as Oh Hwa-soo : Chief Judge of the Seoul Eastern District Court. •
Kim Min-ha as Park Mi-young : A prosecutor at Kang Hyun's office • as Seo Jung-min : An Investigator who works with Kang Hyun.
People around Eun Sol • as Eun Ki-sang : Eun Sol's father • as Han Mi-mo : Eun Sol's mother • Kang Sun-sook as Byeolgyo woman () : Eun Sol's housekeeper • Heo Woong as Eun Ji-sung : Eun Sol's older brother
People around Baek Beom • as Baek Ho-cheol : Baek Beom's father
Police •
Lee Yi-kyung as Cha Soo-ho : He is a chief detective, a police lieutenant, from
Gangdong police station's violent crimes unit. • as Detective Park • as Detective Kang
Others • as Oh Man-sang : A criminals who committed multiple crimes • as Yoon Tae-joon : Oh Man-sang's lawyer •
Yoon Sa-bong as Jang Hoo-nam : Jang Deuk-nam's older sister • Yoo Yeon as Jo Hee-jin : Dong-woo's aunt, Han-soo's younger brother, Gil-ja's daughter •
Go Geon-han as Kim Joon-tae : Yeon Mi-rae's boyfriend •
Yoon Ji-min as Lee Hye-sung : Chief of Thoracic Surgery at Seon Hospital, Jang Deuk-nam's doctor and the criminal who killed Seo Jeong-min •
Ok Ye-rin as Han Seo-hyun - Su-yeon's daughter, a victim of child abuse in kindergarten ==Production==