Christopher is a vampire. He was infected by Justine in the 60s. Because he loved his parents, Betty and Arnold so much he also turned them into a vampire. However in the 70s he went missing. Arnold and Betty have not heared from him since then.
It turned out that Christopher had been feeding from children in the 70s. He killed a lot of them and the police got suspicious. So Herrick warned him and told him to feed from pensioners. Christopher did not not stop. So Herrick send Mitchell to Christopher. Mitchell locked Christopher in a cellar and filled it with cement. Chrisopher screamed at first after Mitchell, then he cried for his mother and then the crying stopped. It is not known if Christopher has managed to get out somehow, if he died in there, or if he is still stuck in there, alive and unable to get out.
It is hinted that Christopher might have been one of the vampires that killed Kemp's wife Maria and their daughter. Since there were two male vampires who killed them and who drank the blood of Kemp's daughter it is unknown which one of them is Christopher.