A soldier slit his ex-girlfriend's throat from "ear to ear" just days after she had told police she did not want him arrested for harassment, a court heard.
Lance Corporal Trimaan "Harry" Dhillon broke into Alice Ruggles' ground-floor flat in Gateshead and severed her neck, Newcastle Crown Court heard.
Dhillon denies murdering the 24-year-old former Northumbria University student, who was originally from Leicestershire and worked for Sky in Newcastle.
Ms Ruggles contacted Northumbria Police after they split as she was concerned about Dhillon when he travelled from Scotland, got into her back yard and knocked on her bedroom window late at night.
He allegedly left her flowers and Ferrero Rocher chocolates and then walked away.
Dhillon was ordered by his commanding officer to stay away from his ex but he posted her a parcel containing photos and a letter.
Ms Ruggles phoned police again and was asked if she wanted Dhillon arrested.
Richard Wright QC, prosecuting, said: "Sadly, the dilemma this young girl was in is obvious.
"She was scared and worried about the behaviour of the man she had plainly loved and cared for.
"Generously, she told the officer she did not want him to be arrested.
"She could not have known she would pay for that decision with her life just five days later."
According to the prosecution, Dhillon again drove to Ms Ruggles' home on 10 October 2016 and waited for her while making a causal arrangement with a woman on a dating app.
After he broke in through her bedroom window there was a violent struggle which was heard by a neighbour upstairs, Mr Wright said.
He said Dhillon drew the blade across Ruggles' neck six times. His victim also suffered a wound to the nose and her hand along with chest injuries.
Although the murder weapon was not found, a knife was missing from the kitchen, the jury heard.
A recording of the 999 call made by Ms Ruggles' flatmate Maxine McGill after she found her covered in blood on the floor was played in court.
Ms Ruggles and Dhillon got in contact in October 2015 after he spotted her photo on a mutual friend's Facebook page and thought her to be "the most naturally beautiful woman in the world".
But they did not physically meet until January and their relationship raised concerns because of its intensity.
The prosecution said Dhillon checked her messages and questioned why she was trying to look nice when she went out, the court heard, while he was regularly using dating apps behind her back.
Mr Wright said: "It was plain she had truly fallen for this defendant, but at the same time she couldn't trust him and she knew that his behaviour was controlling and inappropriate and she began to try gently to extricate herself from the relationship.
"She met with fierce resistance from the defendant."
The trial continues.