One-eyed killer Dale Cregan admitted to a psychiatrist that he killed a father and son before going on to murder two police officers, a court heard.
Cregan, 29, has admitted the murder of Pcs Nicola Hughes and Fiona Bone in Hattersley, Greater Manchester, in September last year, but is on trial for the murders of David and Mark Short in the months before, which he denies.
A consultant forensic psychiatrist told Preston Crown Court of statements made by Cregan during three interviews while he was on remand in HMP Manchester.
In one interview, Cregan allegedly admitted all four killings and said he had "the best sleep of my life" after the brutal murder of David Short.
Cregan also said he was a drug dealer who earned up to £20,000 a week, he was paranoid that the Short family were trying to kill him and he had "fantasies" about murdering David Short.