I Think there are many many possibilities 
Including 
Bret stiles
Walter mashburn
Gale Bertram
Virgil Minnelli
Bob Kirkland
Jj laroche
Brett partridge
But one that not many think of... Janes Father, im unsure of his whereabouts and if he is still alive or not, but jane did walk out on him in the show business, it makes sense, he would have know patrick well before he started his murders, Im quite muddled on dates and what not but that is my theory