Quoting a Sir Walter Scott poem, Crown prosecutor Peter McGrath, SC, began his closing address to the jury at the murder trial of Daniel Jack Kelsall.

It was a fitting line to end the trial of Mr Kelsall, an avid reader and "bookworm", who is accused of following Sydney businessman Morgan Huxley home from The Oaks Hotel, Neutral Bay, and stabbing him while he lay in bed.

Mr Kelsall has told the jury that he met Mr Huxley in the early hours of September 8, 2013, and the pair went into his flat for a sexual encounter, which was interrupted by a random attacker.

In his address, Mr McGrath referred to the set of lies Mr Kelsall acknowledged he told police in the weeks after Mr Huxley was killed, including that he had never been inside the 31-year-old's flat, had never met him, and didn't know anything about the killing.

The prosecutor showed the jury excerpts of Mr Kelsall's recorded interview as evidence of him "calmly and methodically lying to police".

Mr McGrath said that for Mr Kelsall's version of events to be true he would have had to be the victim of bad luck and terrible coincidences, urging them to look at the objective evidence.

The trial has heard that Mr Kelsall's fingerprint was found on Mr Huxley's bedroom door, and his DNA was on Mr Huxley's penis. Mr Huxley's blood was found on Mr Kelsall's shoulder bag.

CCTV footage showed Mr Huxley leaving the pub, with Mr Kelsall walking quickly in the same direction.

Mr McGrath said evidence that Mr Kelsall told his doctors about violent thoughts he had been having was "key" to the circumstantial case.

"Who is this young man who had all this bad luck on this night?" Mr McGrath asked.

"Chillingly he just happens to be someone who had experienced intrusive, recurring, persistent thoughts about killing someone with a knife on the way home from work - a total stranger, someone random.

"To the extent that he told [his GP] he actually on one occasion took a knife home from work one night with the thought of stabbing someone. But thankfully, luckily, he did not meet anybody.

"Members of the jury, Morgan Huxley was not so lucky."

Defence barrister Christopher Watson said police unfairly targeted Mr Kelsall as a suspect, without properly investigating other potential leads.

"You observed him ... he's socially awkward, he's not a person who is overly engaging and he has some difficulties communicating," Mr Watson said.

"The importance of that is he sets himself up as an easy target and the police, of course, have targeted him when they saw the CCTV video.

"They targeted this accused at the exclusion of a lot of other aspects that they could have and should have looked into."

Mr Watson said there was no blood found on Mr Kelsall's work clothes, or his boots, as would have been expected after a stabbing.

"In all the circumstances, with all the material that is before you, it's a situation where the circumstantial aspects of this case there are alternate theories and alternate explanations."

The jury retired on Tuesday afternoon to consider its verdict.