Think of it: If a previous Hollyoaks spin-off (think it was screened in 2005 or 2006) revolved around Steph Dean being haunted by the spirit of a dead woman, then maybe the five 'suspects' are all just red herrings and that the real culprit is someone that you wouldn't expect!
Then again, Hollyoaks is meant to be based on reality, so my theory is probably wrong anyway.....