In the intervening days, the warehouse worker posted photos and derogatory comments on Facebook about the University of Kent student and part-time barmaid.
McLaren had blocked Stimpson on social media, but learnt of his comments and reported the posts to police on June 22.
The previous day, McLaren had told a relative she feared Stimpson would hurt her.
Describing him as "manipulative and turning nasty", she said: "I am actually scared about what he might do. I'm scared he might hurt me. I don't know how on edge he is."
During the killing, Benjamin Morton, a witness, tried to pull Stimpson off McLaren as she screamed.
Joshua Stimpson is on trial for the murder of Molly McLaren. Photo / Facebook
Morton later told police Stimpson was "continuously" stabbing McLaren, mainly in the neck area. He added: "It was like a frenzy, he was doing it again and again."
McLaren, who studied sport, exercise and health, had just been to a gym. Stimpson had been at the same gym and she asked him: "Are you following me now?"
She also sent a WhatsApp message to a group of friends at 11.02am, saying: "Feel like I'm f***ing looking over my shoulder all the time".
It was her last communication.
Prosecutor Philip Bennetts QC said as she walked to her car, CCTV footage showed Stimpson waiting for her in his vehicle and then begin to tail her. He left his car, walked quickly to hers and yanked the door open as McLaren screamed.
Joshua Stimpson pictured on CCTV footage purchasing a knife. Photo / Kent Police
Stimpson, who admits manslaughter but denies murder, was arrested at the scene, covered in blood. The court heard he had told a work colleague he suffered from bipolar disorder.
Two days before the killing, Stimpson bought a Sabatier paring knife from an Asda store in Chatham. It was found on the driver's seat of McLaren's car after she died.
