She had recently left home and was working as a shop assistant. In the course of a heartbreakingly normal night out, she had met a lad in Leeds city centre and danced with him until the last bus home. Sitting on a bench near St. James Hospital, they had shared a bag of chips - doubtless flirting and laughing with all the innocence of carefree youth.
After he had left, she started to make her way home. Failing to find a taxi, she decided to walk the remainder of the way home. Her route would take her past the Gaiety pub where Sutcliffe had already waylaid Emily Jackson and her ultimate location - her house at 77 Scott Hall Avenue - was just six doors from the home of Wilma McCann.
The final grisly coincidence was Sutcliffe's drive up the road that night. Seeing her walking alone in a red light district, he assumed she was a prostitute and followed her on foot. As she walked down Reginald Street past an adventure playground, he struck her with his hammer, then dragged her body 20 yards to a more secluded spot.
There he pulled her clothes into disarray and stabbed her variously 20 times in the back and front. When police turned her body onto its back, they found a broken bottle embedded in her chest.
Jayne McDonald was no prostitute - although Sutcliffe has assumed she was. She hadn't even had a drink of alcohol that night.
These facts, coupled with her age and aching prettiness, turned the Ripper into a public monster. A lot has been said and written about how his first victims were often dismissed as 'just' prostitutes, and the outrage over Jayne's murder shows that those claims have merit. As long as Sutcliffe was targeting fallen women, 'normal' people could feel safe but now, seemingly, all bets were off.
Even Sutcliffe himself felt that this murder was significant - if only in hindsight. In his statement, he would say:
"When I saw in the papers that MacDonald was so young and not a prostitute, I felt like someone inhuman and I realised that it was a devil driving me against my will and that I was a beast."