There are a lot of people on other fan sites now convinced that Dylan is the killer (especially given his behaviour in recent episodes etc). But, I must agree that it will be extremely disappointing if it does turn out to be him. And I just have to mention what I said in a post a couple of weeks ago "With the investigation app that Ch7 put out to go thru all the main suspects etc, & then all the adverts like "all of them have a motive, but one of them did it!" & "one of your favourites is a killer!" which were being shown all the time over the summer break etc (before Dylan even arrived in SB!) & then "it is someone everyone knows really well", again, it will be really, really disappointing if it turns out to be Dylan."
If it is not him, then there is not many others left now who it could be. I outlined quite a while ago the reasons why I thought that it could be Andy & I still think it could be him. With Kat now discovering who the killer is, these latest articles say that "Because of her relationship with the killer......." & "As Kat prepares to come face to face with a murderer - who she clearly knows well.....". That could mean that it is Dylan, with the relationship they had, or maybe it could mean Andy? - not having a "romantic" relationship with him, but she has a "business" relationship with him (she invested in the garage) & he is Ash's mate etc. Of all the people who had a motive, Andy seems to be about the only one left who hasn't been interrogated by the police (on screen anyway). Having said that, I am probably wrong & wouldn't be at all surprised if it is Dylan, even though they have lead us to believe (again!) that it would be a regular/fulltime character. (It will be interesting to see whether, after being involved in the incident/fight which causes the explosion, & the death of 2 characters etc, Andy is also found out to be Charlotte's killer as well!!).