FIRST THING…IS HE NEUTURED?…IF NOT THATS A PROBLEM…ALSO BY YOU LETTING HIM GO OUTSIDE AT WILL HE SEE,S YOUR HOUSE AS PART OF HIS OUTSIDE….I WOULD SHUT THE KITTY DOOR…IT MAY SOUND MEAN…BUT ITS EAITHER THAT OR HAVE A HOUSE THAT SMELLS LIKE A CAT BOX…..