Five months ago,, Kim Namjoon was found in a pool of his blood in the dorm bathroom. Blood was splattered over the walls and on the ceiling where he was discovered to have shot himself.
Namjoon had never done anything this insane before or even thought about suicide.
Yoongi knew something was seriously wrong, he knew Namjoon wouldn't shoot himself nor do it without a suicide note. That's how he found out Namjoon's death wasn't suicide...
It was murder.
Yoongi, finding this out, put him and all his friends down as suspects for the homocide of Kim Namjoon.