The moment Julia James was killed was tracked by her watch, a court heard on Monday.
The police community support officer (PCSO) was ambushed while out walking her dog and subjected to “a brutal and fatal attack” in Ackholt Wood, near her home in Snowdown, Kent, last year.
Callum Wheeler, 22, from Aylesham, Kent, admits killing her but denies her murder, Canterbury Crown Court heard on Monday.
Canterbury Crown Court heard on Monday that the moment James tried to make her escape from her killer was captured in heart rate and walking speed data recorded by her Apple Watch the day she died.
Prosecutor Alison Morgan QC told jurors her movements and biometrics were being tracked by the device as she walked into the woodland where she was killed.
Morgan said: “We saw now the pace she was going at and the moment her pace radically changed and that’s plotted by the data from her own watch.
"We also know about her heart rate. A relatively stable heart rate through the part when she was walking. That at 14:30 and 36 seconds her heart rate was 97 beats per minute.”
Watch: Man charged with murder of PCSO Julia James
Morgan said that moments later it had “launched” to 145 beats per minute, adding: “And that launch is something I will come back to as to where she was and details the escape she was doubtless trying to make at that moment.
“It was at that point that her heart rate surged.”
The court heard that James, 53, had spotted Wheeler in the woods a number of times before she was attacked.
On one occasion, about two months before her death, she pointed out a man - alleged to have been Wheeler - to her husband, Paul James, and described him as a "really weird dude".
Prosecutor Alison Morgan QC said Wheeler repeatedly visited Ackholt Wood, where Mrs James would regularly walk her dog.
Ms Morgan said: “On one of those earlier occasions when he was in Ackholt Wood, he saw and was seen by Julia James herself.”
She said Mrs James “was herself aware of the presence of a strange male”, who she described to her husband as a “really weird dude”.
She later pointed out the man, alleged to have been Wheeler, to Mr James during a walk together in February 2021, about two months before her death.
Mrs James was found dead after she had gone out with her Jack Russell dog, Toby, on 27 April last year.
Ms Morgan said: “The evidence suggests that her attacker was waiting in the woods for someone to attack and then ambushed her.
“Julia tried to escape her attacker but she was subjected to a brutal and fatal attack.
“She suffered catastrophic injuries and died where she fell.”
Ms Morgan said it is the prosecution’s case “that there is a large body of evidence from a variety of sources that demonstrate that the attacker was this defendant Callum Wheeler”.
She told the court: “Although he denied responsibility for the killing for some time, he does now accept that he was the person that killed Julia James, however he does not accept that he is guilty of the offence of murder.”
Ms Morgan said Mrs James was killed with a metal railway jack, which she said was later found in the defendant's home.
She said: “A heavy blunt object was used to murder Julia James and when we come on to consider her injuries you will understand why it must have been an object of that type that killed her.
"In fact, the prosecution alleges, and there may now be no dispute, that the weapon was a large railway jack.
“That item was found in his bedroom.”
Jurors were played footage from police body-worn video of an encounter between officers and Wheeler when he dialled 999 on 17 April 2021, 10 days before Mrs James died.
Ms Morgan said: “He did not give a coherent reason for calling the police and he did not invite the police officers into his property.”
The footage showed Wheeler telling the officers “get lost, mate” and “I’m not talking to you”, before his father reassured them he was okay.
Ms Morgan said: “You may think that the footage of this visit shows the defendant to be behaving oddly” and told the court that he had been reluctant to have “any meaningful conversation with the police”.
The trial continues.
Watch: Police reconstruct walk taken by PCSO Julia James