Jin Sun was a hacker working with Wujing to decode encrypted messages for their assassination targets.
Jin Sun knew the mentor that Elizabeth Keen claimed to have trained with for her cryptography skills.
He was Wujing's new cryptographer. Elizabeth Keen put her remote mirroring device into his computer. When Wujing's security program detected the external access he was beaten by Wujing. As he lay on the floor he noticed the USB key, but before he could tell anyone about his discovery he was shot and killed by Raymond Reddington.