He gives a rather choppy and hurried explanation when he is surrounded in the park, but tbh I wasn't any wiser afterwards. I don't think it makes any kind of sense. After all, every murderer has, collectively, thousands of relatives, friends, people who know them in passing, work colleagues etc. Admitting that 'Hey, I knew that guy!' is hardly a reason to think you were a conspirator. You'd think a cop would have a better grasp of what constitutes evidence. But wtf, it's just a crime romp, not a documentary I guess.