Benjamin Field, 28, said a fascination with literature and also his work in an elderly care home was behind his attraction to the subject.
He is on trial alongside Martyn Smith, 32, accused of murdering Peter Farquhar, 69, and conspiring to murder retired headmistress Ann Moore-Martin, 83, in order to benefit financially from their wills.
Field, the son of a Baptist minister, admits deceiving the pair, who were neighbours in the village of Maids Moreton, Buckinghamshire, into believing he was in a relationship with them both.
Field, was being cross-examined on the ninth day of giving evidence at Oxford Crown Court.
Oliver Saxby QC, prosecuting, asked Field why he owned copies of books and essays about death, including Five Last Acts, Easing The Passing and The Savage God, as well as a copy of the film Young Poisoner's Handbook.
"I did think I was comfortable with death," Field replied.
"I had been working at Red House care home for three months and seeing death and dying for the first time and a lot of it.
"It was something that had become part of my life. I thought I was getting there and looking back it was a scab constantly picked by me."
Mr Saxby asked Field about internet searches he had carried out for "bleach suicide", "most prolific executioner" and "cyanide poison", and Field explained this was for "entertainment" rather than "pleasure".
He also accessed posts on an internet chatroom about "injecting testicles with lactic acid" and "bleach enemas".
Asked about this, Field replied: "I was interested in death and I was working in an end-of-life setting."
The jury also watched a video clip filmed by Field in the care home of him taunting an elderly woman about loneliness, pain and death.
Asked about the clip, Field said: "It's horrible, cruel, a revolting thing to watch."
Mr Saxby drew comparisons to Mr Farquhar and asked: "Not in a two-minute videoclip but over the course of a year?
"Did you try and break him down, so that he became so full of despair and talk to him about death in the hope that he might kill himself?"
Field replied: "No."
The jury also heard Mr Saxby ask the defendant whether he was good at planning.
"You did kill Peter Farquhar and you tried to kill Ann Moore-Martin. Getting them to change their wills requires a degree of planning?," he asked.
Field replied: "It would, if that had happened."
Mr Saxby said: "You are someone clearly adept at devising and carrying out plans?"
Field replied: "I don't think so."
Mr Saxby suggested: "It would require a willingness to lie, not just for the sake of it, but in furtherance of the plan.
"Are you willing for pain to be inflicted for the furtherance of one of the plans?"
Field replied: "Not really, no."
Mr Saxby said: "It would involve as a characteristic getting someone to change their will, it would involve an idea with the 'extremes of death' - and that is an enormous thing to do.
"To accept that you have an ease with the extremes of death and the idea of killing."
Field replied: "I have an interest but not an ease."
Mr Saxby said: "A certain arrogance - that sense of you can do it and get away with it."
Field replied: "If I was to do it and get away with it, that would be correct."
The court also heard that the police had covertly recorded conversations Field and Smith had while being transported to the magistrates' court, in which Field talks about "getting away with it".
Field was asked what he meant by the comment and he replied: "In the sense I hadn't done them, so I wouldn't be found guilty of them and the charges were nonsense."
Benjamin Field and Smith deny charges of murder, conspiracy to murder and possession of an article for the use in fraud.
Field, of Wellingborough Road, Olney, Buckinghamshire, also denies an alternative charge of attempted murder. But he has admitted four charges of fraud and two of burglary.
In addition Smith, of Penhalvean, Redruth, Cornwall, denies two charges of fraud and one of burglary.
Cambridge University graduate Tom Field, 24, Benjamin Field's younger brother, of Wellingborough Road, Olney, Buckinghamshire, is also on trial accused of a single charge of fraud.
The trial was adjourned until Monday.
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