Ian Brady, the Moors Murderer, remains utterly unrepentant about his crimes and if ever released would kill again as easily as "swatting a fly", according to the criminologist who has carried out the first face-to-face interviews in a decade with the notorious serial killer.

The 73-year-old Scot, who murdered five children with his lover Myra Hindley in the 1960s, told Dr Chris Cowley that he "wishes the world ill" and refers to the killings as an "existential exercise" which he dismisses as "that Moors business". Brady, who has been held at Ashworth high security hospital on Merseyside since 1985 after he was declared criminally insane, stopped all visits in 1998 and refuses to talk to psychiatrists and social workers, saying: "I will never tell them anything, ever."

But Dr Cowley began writing to the killer in 2002 and admits to a "quid pro quo" with Brady, where he sent gifts like pens and music tapes "and he would tell me things in exchange" in letters and interviews.

Writing in a new book, which is published this week, Dr Cowley maintains that Brady still "carries a torch" for Myra Hindley and mentioning her name prompted rare "glimmers of human feelings". The forensic criminologist paints a picture of Brady as a sociopath with a penchant for intellectualising his killings and who sees any attempt by him to express remorse as "just bringing up ancient history".

Dr Cowley said he had reached the conclusion that Brady remained dangerous: "He would kill again without any thought for anyone who gets in his way.

"For him, it's like swatting a fly, which is how he regarded the children he murdered."

Brady, who has been on hunger strike for eight years and is force-fed twice a day after the High Court refused to overturn a decision to keep him alive, says he is "the resident folk devil" in Ashworth, a place that is a "limbo of the walking dead".

He spends his days in a 12ft by 8ft cell with a window that looks on to a brick wall and claims he has been forcibly drugged and subjected to sleep deprivation.

He wants to go back to prison, saying: "After over 44 years of prehistoric captivity I expect and ask for nothing except to return to prison."

The killer describes his sentence as: "An execution lasting 40 years and they want to drag it out for another 20."

The book, Face to Face with Evil: Conversations with Ian Brady, reveals that the Scot thinks he could have escaped from the police by shooting his way to freedom when they arrived to arrest him and Hindley in 1965.

He said: "Why I didn't shout and block, when she opened the back door to the police unwittingly, is an imponderable still. Even with the sprained ankle I might have reached upstairs [where his gun was] in time."

Brady claims had the two escaped from the police, they "intended to retire young or die in the attempt". He also claims he could have also slipped his captors on at least two later occasions – opportunities Dr Cowley suspects were spurned by the killer in the mistaken belief he would get a normal life tariff offering eventual release.

Brady does not reveal any new details of the crimes or give any indication of where the body of 12-year-old Keith Bennett – the only victim yet to be found – is located. And the Glasgow-born murderer makes it clear that he has no love for his fellow man: "I wish this place and this country and this world ill." When asked if he thinks he is mad, Brady replies: "Perhaps the absence of any obvious symptoms of insanity after being locked up for life could indicate that I might very well be insane."

The book has reopened old wounds for Winnie Johnson, mother of Keith Bennett. Aged 12, he was snatched in 1964 as he walked to his grandmother's house. He was the third victim and, like the others, was buried on Saddleworth Moor near Manchester. His mother said: "I knew nothing about this book. It would have been nice if someone had contacted me so, through the doctor, I could have put questions to Brady."