YOU SAID:
know one else was in the room where it happened
INTO JAPANESE
誰かが起こった部屋にいたことを知っている
BACK INTO ENGLISH
I know that someone was in the room where happened
INTO JAPANESE
私は誰かが起こった部屋にいたことを知っている
BACK INTO ENGLISH
I know that someone was in the room where happened
That didn't even make that much sense in English.