I have questions about "Mouse" (Spoilers) - Please help

I am currently watching episode 5.
1. How was Lee Kyu-hyung able to identify the identity thief?
The thief even had Hyun Bong-sik work in the parking lot specifically to avoid leaving a trail...
2. How did Lee Kyu-hyung find his way to the island where Ryu Jun-yeol is located? There were no apparent clues...
3. How did the hunters find the island and know the locations of Ryu Jun-yeol and Seol Kyung-gu?...