He sat at a table until closing time, sending text messages, and occasionally looking up at a television.

Across the road in Neutral Bay, Daniel Jack Kelsall stood outside a takeaway shop talking to a security guard.

As Mr Huxley left the pub in the early hours of September 8, 2013, CCTV cameras captured Mr Kelsall walking quickly in the same direction.

Mr Kelsall, a cleaner at the nearby Sydney Cooking School, is now on trial, accused of following Mr Huxley to his Watson Street flat and fatally stabbing him. The 22-year-old has pleaded not guilty to a charges of murder and indecent assault.

Crown prosecutor Peter McGrath, SC, told the NSW Supreme Court jury that the scene on the street had played out in Mr Kelsall's head 16 months earlier.

In May 2012, Mr Kelsall told a doctor and a psychiatrist that he had "intrusive thoughts" about stabbing someone on the way home from work at night.

He told psychiatrist Matthew Boulton that he had thought about "killing someone else for the thrill of it" and it would "probably be a total random with a knife", Mr McGrath told the jury.

But when asked if he wanted to kill someone, Mr Kelsall replied "absolutely not".

At 1.30 that September morning, Mr Huxley's flatmate, Jean Redmond woke when she heard two knocks on the door of their flat.

Ms Redmond told the court she was woken again by some noises coming from Mr Huxley's bedroom about an hour later.

"I heard some shuffling around. I heard some high-pitched noises ... then I heard what I thought was a fall or a thump," Ms Redmond said.

When Ms Redmond got up to check on Mr Huxley, she found the 31-year old lying in the doorway of his bedroom, covered in blood, with his shorts down.

A post-mortem examination found that Mr Huxley had 28 stab wounds to his upper body, and the tip of a knife was found lodged in his skull.

The jury was told that Mr Kelsall's DNA was found on Mr Huxley's penis, and his fingerprint was found on the bedroom doorway. Mr Huxley's blood was found on Mr Kelsall's shoulder bag.

The court heard Mr Huxley would sometimes leave the door of the flat unlocked, and it wasn't unusual for him to have visitors at night.

Mr Kelsall's barrister, Christopher Watson, said his client would give evidence during the trial to address some of the evidence.

"The most damning aspect ... against the accused is of course the deceased's DNA on his bag. It must be the case at least that the bag, and by inference, the accused is proximate to the deceased at least at the start of when some harm  ... is caused to him.

"Mr Kelsall will give evidence to address that aspect in this case."

The CCTV footage would simply show Mr Kelsall following his usual route back to the cooking school, where he thought he left a light on, he said.

The trial continues before Justice Robert Allan Hulme.