YOU SAID:

But no-one else was in the room where it happened, the room where it happened.

INTO JAPANESE

だが誰も居なかったその部屋で起こった

BACK INTO ENGLISH

But no one was there. It happened in that room.

INTO JAPANESE

だが誰もいなかったあの部屋で起こった

BACK INTO ENGLISH

But no one was there. It happened in that room.