Ushek San'ko was the leader of F. R. C. He was also Sark's contact after he was broken out of custody.
Before Season 3
San'ko had a brother who was accidentally killed by Sark due to a misplaced car bomb.
During a trade gone wrong between Sark and a CIA agent, San'ko appeared and rescued Sark during the confusion, taking him to a clandestine location. When they got there, Ushek offered Sark some wine and began to remenisce about his dead brother...who was presumably killed by Sark. Even though Sark thought he was about to be killed, Ushek offered a different deal: 800 million dollars. Since Sark's father was supposedly killed, Sark was able to give San'ko the money, thus beginning their business relationship (Succession).
Sark and Sydney (posing as Lauren) arrived in San'ko's nightclub to discuss the whereabouts of a chemical bomb that he hired Anna Espinosa to steal. However, before San'ko agreed to help them, he wanted to see Lauren and Sark kiss each other lustfully, as he got off on that type of pleasure. Sydney kissed Sark while he had a lime in his mouth, biting his lip in the process, and San'ko agreed to tell them about the bomb. However, as San'ko poured himself more wine, Anna shot through the glas and hit San'ko in the throat. He soon died afterwards (A Man Of His Word).