He was found out to be a fake!
Ciaran O'Keeffe, the shows Parapsychologist, had suspicions about Derek being a fake. None of the other members of the crew realised this though. So on one of the investigations Ciaran mentioned to a member of the crew that someone called Kreed Kafer (Ciaran had made up this name) was haunting that particular building. He made sure he said it within earshot of Derek.
Then I think Derek got possesed by someone he called 'Kreed Kafer'. This is how they knew he was fake. Kreed Kafer is a completely made up name and turns out to be an anogram of 'Derek Faker'.
Derek Acorah left the show in the midst of controversy. He agreed to film a final season before going on to be in other shows. He has also authored several books on the paranormal.
Because he got exposed as a fake. Just google it and you will gets LOTS of hits.
leave
I don't really know about that but if your friend is doing the ouiia board in any room, make sure that the tell them to leave afterwards because otherwise they might not leave and so you might get haunted. That's what happened to my room, but then afterwards it didn't leave so we had to use the board again and we had to force it to leave.
The Haunted - 2009 Leave House 1-7 was released on: USA: 20 January 2010
Because he's an idiot
Dr Derek McCormack left Celtic on mutual understanding.
I
The Haunted - 2009 Leave or Die Ghost Town 1-10 was released on: USA: 19 February 2010
They were usually abused in the home that is being haunted or they didn't believe in Jesus and died in the home and did not want to leave their home
Leave the Haunted House through the basement and go right to where you entered, at the far right. There is an open hole (grave) that is the entrance and exit. You will exit to the Island Map, not where you originally came from.
Leave It to Beaver - 1957 The Haunted House 2-23 was released on: USA: 5 March 1959 Finland: 27 May 1962