A smartwatch captured the final movements and surging heart rate of police community support officer Julia James as she was chased by her killer, a court has heard.

Julia James, 53, had been taking her usual route through Ackholt Wood in Kent with her Jack Russell dog Toby when she was “ambushed” by 22-year-old Callum Wheeler on 27 April last year.

Canterbury Crown Court heard how the mother’s Apple Watch data showed her heart rate suddenly spiked at 2.30pm before she took a detour out of the woods and along the edge of a field.

The prosecution argues she was attempting escape Wheeler, who was allegedly seen “roaming” the area with a metal railway jack 24 hours before Ms James was attacked and had previously been seen in the woods by the police community support officer (PCSO) and her husband.

Prosecutor Alison Morgan QC told jurors Wheeler, from Aylesham, Kent, now accepts he killed Ms James but denies murder.

She told the court Ms James’s watch showed her heart rate had gone from 97 up to 145 within seconds at 2.30pm, when it is believed she spotted Wheeler in Ackholt Wood.

Her heart rate then dropped off and there was no further movement after 2.35pm, before Ms James’s last heart rate was recorded at 2.43pm, she said.

Ms Morgan told the court: “The defendant was in that same place that Paul James and Julia James had seen him before, and it was at that point that Julia James’s heart rate surged.

“She took a sudden detour off the path that goes through the wooded area.

“She began to move along the edge of the field.”

The prosecutor added: “She has run out of the wood, doubtless to try to escape her attacker, and has got as far as she could along the path.

“She was chased by her attacker and it is likely that as she ran she fell either from the first blow from her attacker or by tripping because we know from pathology evidence that her left wrist was fractured.

“Once down on the ground she was then subjected to what the pathologist who examined her body described as a violent and sustained blunt force trauma assault to the head, especially concentrated on the top and the back of the head.”

The prosecution alleges Ms James was killed with a metal railway jack which, they say, was later found in the defendant’s bedroom.

Ms James suffered “catastrophic” head and brain injuries which would have been “completely unsurvivable even with immediate medical intervention” and would have died very quickly, according to the pathologist who carried out a post-mortem examination of her body.

The pathologist concluded there were “no signs of sustained or violent sexual assault” but that “the lack of such injuries would not necessarily rule this out,” Ms Morgan told the court.

Several members of Ms James’s family attended court to hear the prosecution open the case.

The trial continues.