in last episode "RED TATTOO" when she opened the door for red john "if he is the knocker" she looked straight along her sight so exclude tall suspects gale, sherrif,ray.

we have reede , brett,

smith does't look intelligent neither serial killer which leave brett

another idea what make partridge goes to abandoned house unless he knows is spied he observed Lisbon outside make some noise to attract her and the voice of red john every time we hear match brett's voice coldish and stolid.