On a December night in west London, Fatima Khan approached her boyfriend as he lay dying from multiple stab wounds on the pavement.
But instead of helping him, or even calling emergency services, she took out her mobile phone and videoed him.
Witnesses who were trying to help the fatally injured man, Khalid Safi, challenged her, asking what she was planning to do - put the video on social media?
That is exactly what Fatima did.
She posted the image of her dying boyfriend on Snapchat with a warning that that was what happened when people messed with her. She used an expletive instead of the word "mess".
Ilford's 'Snapchat queen'
The 21-year-old self-confessed "Snapchat addict" orchestrated the killing of Khalid.
She arranged for a rival for her affections, a man called Raza Khan, to kill him, her trial at the Old Bailey heard.
CCTV images showed her calmly filming the scene of the attack as she talked on another phone to her accomplice while he was making his escape.
As with all Snapchat videos, the pictures would have been automatically deleted within 24 hours.
However, one of the group of friends who followed her online posts filmed the message and two years later it re-emerged as the key evidence in her trial.
Fatima's own defence barrister told the jury how she seemed to live her entire life on social media.
"She may be Ilford's Snapchat queen," Kerim Fuad QC said.
"I don't say that to make light of it," he told the court. "She's another example of youngsters who seem to live their life through the prism of Snapchat.
"It's a product of a mobile telephone driven obsession. It's not healthy," he admitted.
The trial heard how 18-year-old Khalid was stabbed to death on 1 December 2016.
The teenager had been the on/off boyfriend of Fatima for several years. However, 19-year-old Raza had also had a previous relationship with her.
She would Snapchat Raza on a daily basis as part of a group chat.
The two rivals - Raza and Khalid - had previously had a fight over Fatima, during which Khalid was stabbed.
Later, Fatima complained to her friends about Khalid being "too clingy" and in the days leading up to his murder the court heard how things "were clearly coming to a head".
He had bought Fatima a watch as a present, but when he visited her she threw it out of a window because she was angry he had come to her house.
Digital murder diary
Fatima had "willingly and knowingly" agreed with Raza to kill Khalid, the court heard.
She told Raza where to find him and made sure Khalid was in the right place when he arrived by minicab in North Acton on the night of his death.
CCTV showed Raza walking over to Fatima with witnesses describing him as carrying a large knife.
Fatima was also said to be unsurprised by his sudden arrival.
After a brief fight, Raza stabbed the victim in the heart and ran off. His whereabouts are still unknown and he remains a wanted man.
"Fatima Khan did not call the emergency services, she did not ask anyone else to do so and she did not try to assist Khalid Safi at all herself," Prosecutor Kate Bex QC told the trial.
"Instead she returned to the scene after Raza Khan had inflicted the fatal wounds and videoed Khalid Safi as he lay dying in a pool of blood."
On the day of Khalid's death, the images Fatima posted on Snapchat amounted to a digital diary of a murder.
She told police she had argued with her boyfriend - on the way to the scene she had filmed part of the row on her mobile and posted it online.
Fatima had claimed she was terrified and had posted the video as a "plea for help", the prosecutor said.
But there was nothing to suggest such fear, the prosecutor added, and Fatima made "no request for help".
Fatima told police she hadn't been able to call the emergency services after the attack as she could not get her fingers to use the keypad of her phone.
But she had been able to post several further messages to Snapchat after the killing.
One showed her taking an Uber taxi home after the killing. The post was captioned: "Uber long life."
Another showed a video of the carpet of her home when she arrived, when she could be heard talking with her parents.
"If she had ever been, she was no longer shocked and acting impulsively by that time," argued the prosecution.
Callous and crass
Fatima never reported the incident - it was a relative of the victim who contacted police days later and gave them her address.
In her defence, she told the court she had wanted to leave the scene before anything happened. But the prosecution argued this was contradicted by the fact she returned to film Khalid as he lay dying on the pavement.
Fatima's barrister said she was "hugely callous - crass even - in taking that image of Khalid on the pavement and posting it with those words.
"If there was a charge for being callous and crass in the aftermath of this shocking incident she would plead guilty to that charge."
Fatima Khan was instead charged with joint enterprise murder, with an alternative of manslaughter or conspiracy to cause grievous bodily harm.
At the end of her four-week trial, the jury cleared her of murder, but found her guilty of manslaughter by a majority verdict.