The man who murdered Libby Squire exposed himself to her just weeks before killing her, her mother believes.
Pawel Relowicz, 28, dumped the 21-year-old student's body in the River Hull after raping her on a playing field in the early hours of 1 February, 2019.
But before that, he had committed a number of other sexually-motivated crimes in the city's student quarter - peering through windows to watch young women and breaking into their homes to steal intimate items.
Lisa Squire said her daughter had been "absolutely furious" after being flashed at, but she did not tell her to report the incident to police.
Mrs Squire told The Guardian: "I never thought to say to her: 'You need to report that, you need to ring the police'.
"And she didn't report it either.
"We're almost conditioned to ignore indecent exposure.
"I didn't know better then, but I know better now."
She was speaking just days after Sarah Everard's killer Wayne Couzens was sentenced for a series of exposure incidents.
The 50-year-old, who was a police officer at the time, exposed himself to a cyclist on a country lane in Kent in November 2020, and then twice to female attendants at a McDonald's drive-through in Swanley, Kent, in February 2021.
The incidents at the McDonalds were just days before he abducted, raped and murdered Ms Everard, 33.
When she sentenced Couzens for the exposure offences, Mrs Justice May said that the fact he was not caught or questioned over the incidents at the time had "confirmed and strengthened in (his) mind the dangerous belief in his invincibility and power to sexually dominate women without being stopped".
Similar comments were made by Mrs Justice Lambert when she sentenced Relowicz in February 2021.
She said to him: "Your offending escalated, you grew increasingly emboldened, no doubt you were increasingly confident you would not and could not be caught".
Mrs Squire said she had been "absolutely horrified" when she learned of the similarities between what Couzens did to Ms Everard and what Relowicz did to Libby.
She admitted that she will never be able to prove that Relowicz was the man who exposed himself to her daughter but she said "the coincidence is there".
"As likely as not, it was "Relowicz who flashed Libby because he was doing that in the area at the time," she said.
"I'll never be able to prove that but the coincidence is there, isn't it?"
Mrs Squire has been campaigning for lower-level sex crimes to be taken more seriously by police and by the courts.
She said: "Not every non-contact sexual offender will go on and become a rapist, but every rapist was a non-contact sexual offender at one point," she said.
"So I think we need to take them for the red flags that they really are."