Earlier quoted context omitted.
Is this common in western countries, or one of those "only in the US and/or some third world country" things, like the "three-strikes" and the "death penalty" (even for juveniles) laws?
In this case, Mr Fennell watched a man get attacked, did nothing to help the man and even actively participated in the attack, and when the man died, Mr. Fennell protected the presumed killer by refusing to testify. I don't think it's a stretch, ethically or legally, to assign him significant blame for the killing, especially since his refusal to testify deprived his victims of any further justice. That doesn't mean…
Do you have any evidence for this, or are you assuming that protecting the murderer was Mr. Fennell's motive? Was he offered immunity for his testimony? If not, then he has very good legal reasons, not to mention the Constitutional right, to remain silent.