His merciless actions devastated so many lives - but who is Callum Wheeler? And what drove him to murder a complete stranger?

A young man of 22, Wheeler lived in Aylesham, near Canterbury, with his dad and brother. But with no job, friends or interests of note, he has been described by police as a "complete and utter loner" whose life "consisted of nothing".

In the months leading up to the brutal murder of much-loved PCSO Julia James in April last year, his presence in Snowdown - a tiny hamlet with just 54 houses - was conspicuous, and set alarm bells ringing among locals.

Even Julia herself felt unnerved after spotting him near her home on numerous occasions, sharing her concerns with her husband about the "weird dude" lurking in the area.

Before the murder, he had lived in nearby Sunshine Corner Avenue for about two years - but cannot be said to have been an active part of the small community.

Having moved to the village from south-east London, where he had lived with his mother, Wheeler spent his days watching television in his bedroom.

A football fan, he would watch matches at the local sports centre most Tuesday evenings, and also enjoyed playing computer games.

But far from your average young man in his early 20s, he had no friends, and a tenuous relationship with even his closest family members.

"During an investigation such as this, we delve into that person's history, and I have to say, very, very unusually, very little could be found about Callum Wheeler," explained senior investigating officer Det Supt Gavin Moss.

"He, for instance, never used social media. He was an individual who didn't have any friends.

"His phone was surprising because it contained basically nothing. He hardly had any contacts, and in life he was an absolute loner.

"He wasn't studying or working. This was somebody who had a life that consisted of absolutely nothing.

"His relationship with his brother - they didn't even know each other, really. He didn't know what occupation his brother had. Not a great deal came from the family."

A reclusive outsider who kept himself to himself, certainly. But a cold-blooded killer?

He had no history with the police, nor of drug use, and searches of his home revealed "nothing to suggest any other criminality".

So what possessed the then-21-year-old to bludgeon a much-loved wife and mother to death as she innocently walked her dog just yards from her home?

The prosecution gave a harrowing account of Wheeler's actions, telling the jury he had "waited for Julia James or another vulnerable female to be in that woods" before "ambushing" and "chasing her down".

"She ran, desperate to get away from her attacker," Alison Morgan QC said.

“Unable to outrun him, he struck her. She fell to the ground, she broke her wrist, then when she was face down on the ground he struck her again and again and again. She had no chance of survival."

Baffled detectives were unable to establish a motive for Wheeler's crime, nor why he targeted Julia - whom he had never met or had any contact with before the killing.

"To be honest, I really don't know why he did it," Det Supt Moss admitted.

"In terms of motive, there's only one person who knows the real answer to that, and that's Callum Wheeler.

"I can only speculate it was just a random attack. What I do know is that it had a profound impact on a great number of people."

Investigators say nothing appeared to have been taken from Julia - although police have never found her house key.

And they say there was nothing to indicate any of Julia's clothes had been removed or that there was a sexual motive to the crime.

Police questioning was to shed little light on Wheeler's thinking.

He gave a no-comment interview following his arrest, except to say he denied the murder.

But his disturbing remarks to custody staff were more revealing, painting a grim picture of a cold killer devoid of empathy or regret.

The prosecution described how he had told workers Julia "deserved to die" and talked of "raping and killing" other women in the woods if he was released.

It was also revealed he had visited pornographic websites in the days before and after the murder, and carried out searches on Google and Facebook of Julia and her killing.

Describing Wheeler as a "highly sexualised" individual, the prosecutor told jurors rape was "plainly" on his mind at the time of the killing.

“He was a highly sexualised individual members of the jury, and his internet search for the word rape, of course, two days before the attack on Julia James, two days before that attack when he found Julia James isolated and vulnerable, one day before he was touring with that weapon, that is what the prosecution say was plainly on his mind.”

She told how Wheeler had exposed himself to female police staff “whenever he got the chance” while in custody, and told officers he “wanted to get women on the ground and rape and kill them”.

In the days following the murder, Wheeler continued to "tour around the local area" carrying the murder weapon.

Mystery continues to surround where he obtained the heavy tool - a handle of a jack typically used to lift train tracks.

He had no connection with the railway, having never worked there, and is not thought to have purchased it lawfully.

Asked whether he might have been searching for other victims, Det Supt Moss replied: "I can never say what was in his mind."

And while Wheeler had a history of mental illness, this was not used as part of his defence. Indeed, his lawyers offered no evidence on his behalf at the trial.

Displaying no sign of remorse for the gravity of his actions, he was pictured smirking and poking his tongue out at waiting press as he arrived at Medway Magistrates' Court for his first appearance in the dock.

And during the trial, his behaviour was to raise eyebrows among those present.

Wearing a dark suit jacket and flanked by four court officials, he could often be seen scanning the courtroom from behind the glass-fronted dock.

Hunched forward in his seat, he would focus on the faces of those in the press bench, up in the packed public gallery and towards Julia's family - sat just metres to his left.

On day one of the trial, Wheeler was seen to feign a soft right-handed slap before the jury entered court, causing one of the dock officers to flinch.

And on another occasion, he was seen unbuttoning his shirt and touching his chest.

Wheeler, who wasn’t handcuffed throughout the proceedings, could often be seen fidgeting with his hands and on one occasion talking inaudibly to dock officials. His mutterings prompted the judge to order him to be silent while the prosecution’s case was being laid out.

While evidence was being presented, he would hunch forward on his seat and dip his head, sometimes for hours at a time.

But towards the trial's conclusion, his behaviour changed. On day five, his body appeared limp, with officials having to carry him to the dock.

Once seated, he assumed the familiar position - crouched forward with head bowed - but could be seen visibly shaking and had to be carried out of court, with the case adjourned for the day.

He continued to deny responsibility for Julia's death until the trial, when it was revealed he had admitted killing the PCSO. But he maintained he was innocent of murder.

Ultimately, his protestations failed to convince jurors, who unanimously convicted him of murder after deliberating for just over an hour.

Wheeler faces a lengthy jail-term when he is sentenced, hopefully providing closure for the many touched by the tragedy - and justice for Julia.