Not a lot is known about Rhee before his arrest and incarceration on SAR TOP, other than that he was a murderer - whose victims included Daggon's wife and daughter. He appeared to have some form of addiction to killing - as Daggon stating that when Rhee killed another, it made him 'excited'. After Rhee's arrest (presumably as a result of fighting and losing to Daggon following his murder of Daggon's family), Daggon himself stopped his job as an educator and was drafted into SAR TOP to become a guard and make sure Rhee didn't escape. When Rhee's brother Remel tried to kill Daggon as a blood oath to Rhee - not caring about the crimes his brother had committed - he ended up incarcerated on SAR TOP himself as a result of failing to complete his vendetta.
When Zin was preparing the jailbreak, he used Rhee as a 'test subject' to see if the wormhole to Earth worked. On Earth, Rhee took the life force of a human female from a XXX Movie Motel and quickly began another murder spree in and around Chicago. However, Daggon followed him to Earth to track him down - taking on the form of an underwear model called 'Cole' - as well as adopting the name. Despite his limited English and understanding of Earth customs, Cole/Daggon was able to gain the help of a woman called Mel, who owned a bar in Chicago called the Watchfire. Working from there, Cole was able to track down Rhee and, with Mel's help, pursued him and managed to catch up - although the engine of Mel's car overheated.
As Cole and Rhee began to fight, Mel fled to a passing car and managed to convince the driver to help her - unbeknown to both her and Cole that the driver was in fact Zin in his human form. During their fight, Rhee used insults in an attempt to aggravate Cole - such as saying about him having 'so much fun' on Earth and noting Cole's struggle with human speech due to not taking a human life force, saying humans teach [the prisoners] so much. When Cole states to Rhee that humans didn't teach him to murder others, Rhee coldly replies "No need - I had a lot of practice with your wife and daughter!"
Despite his efforts and abilities, Rhee is defeated by Cole but still continues to insult him, stating his daughter went slowly. Cole proceeds to hit Rhee with the pole that both of them used during the fight before pulling out his Collector. Replying to Rhee that he will 'go slowly' too, Cole pulls out Rhee's life force - the process temporarily exposing Rhee's life force to Earth's environment and proving very painful for Rhee, as Cole deliberately makes the extraction of his life force slow.
Zin would later reveal to Remel - Rhee's brother who had also escaped to Earth (after Zin had ensured the wormhole worked) and took on the human form that previously belonged to Krace - that Cole had captured Rhee. Zin also stated that during the fight between Rhee and Cole that Rhee was "careless and over-confident" - which was the reason for his defeat. Remel and Cole would again clash, with Remel attempting to gain revenge on Cole. Once again, however, he failed to kill Cole and his life force was captured - with Cole angrily telling him "say hello to Rhee for me" as he pulled out Remel's life force.
Tracker (TV Series) - Episode 1: Pilot
Tracker (TV Series) - Episode 2: Cloud Nine (Mentioned Only)
Tracker (TV Series) - Episode 20: Back into the Breach (Mentioned Only)
Tracker (TV Series) - Episode 22: Remember When (Stock Footage)