One-eyed killer Dale Cregan admitted to a psychiatrist that he killed a father and son before going on to murder two police officers in Greater Manchester, a court has heard.
Cregan, 29, has admitted the murder of Pcs Nicola Hughes and Fiona Bone in Hattersley in September last year, but is on trial for the murders of David and Mark Short in the months before, which he denies.
On Thursday, 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.
Cregan is accused of shooting David Short before tossing a hand grenade at him, blowing his body apart in Clayton, east Manchester, just months after allegedly shooting dead his son Mark Short in an attack on the Cotton Tree Pub in Droylsden, Manchester, on May 25 last year.
After months on the run, Cregan lured Pc Hughes, 23, and Pc Bone, 32, with a bogus burglary report before he opened fire on the unarmed and unsuspecting officers, then using his "calling card" by throwing a hand grenade at the stricken victims.
Dr James Collins, a consultant forensic psychiatrist, told the jury he interviewed Cregan three times in January this year ahead of the trial.
He said Cregan told him David Short had threatened to rape his sister and his son and he was worried the Short family would also harm his other family.
Dr Collins, quoting Cregan from notes he made of the interviews, said: "'I used to get visions of them killing my son, perhaps by a stray bullet. I was also worried about my mother and brother.
"Since I lost my eye it's been worse.
"I thought if I killed David Short I thought all these thoughts would go away.
"I did feel better after killing him. I felt better for a couple of days but all the thoughts came back.
"The paranoia was so bad I used to just sit in the house on my own.
"David Short was the biggest threat. I felt quite good about myself when I killed him'."