MURDERED Libby Squire's mum traced her daughters last steps to find out what happened before she was killed.
Lisa Squire said there are still seven minutes unaccounted for before her death which "gnaws away" at her.
Philosophy student Libby, 21, was dumped in the River Hull after Pawel Relowicz, 26, raped and killed her in February 2019. He saw her on a bench after she was refused entry at a nightclub in Hull.
Lisa told : "It would mean a lot to me [to find out what happened] because I could then piece the last pieces of her life together.
"I knew almost everything about her life but I don't know what happened.
"There are two questions that go through my head - did she cry and where he put her in the water?
"It gnaws away at me and I have to work quite hard to not let it really get to me."
Lisa, who visited the spot where Libby was dumped, added she feels guilty for not saving her.
She said: "I should have known that she was in danger and I didn't.
"I know she would have been scared and she would have wanted me to come and save her, which obviously is the one thing that haunts me.
"I know she called for me."
Dad-of-two Relowicz was sentenced to a minimum of 27 years at Sheffield crown court for Libby's abduction, rape and murder.
Lisa has previously said she wants to question him in prison on how her daughter died.
She wants to know how she got into his car and whether she was dead when she went into the water, among other questions.
She told BBC Breakfast: "My children are a massive part of my life so not knowing what happened to her, for me, is not acceptable."
Lisa, of High Wycombe, Bucks, plans to meet Prime Minister Boris Johnson next week. She has previously called for mandatory whole life sentences for those convicted of rape and murder.
She also wants tougher measures for minor sex offences like indecent exposure and voyeurism.
Before he killed Libby Squire, Relowicz had a history of convictions for non-contact sex crimes including voyeurism.
Lisa said: "People still think that non-contact sexual offences are harmless but they're not harmless.
"We can't say that all people who commit a non-contact sexual offence are going to go on to become rapists and murderers, but I think we can probably say that most rapists and murderers started off with non-contact sexual offences.
"I also think these people need help. There should be some sort of help facility for them.
"They should be forced to go into treatment or have therapy for what they have done.
"Because of what happened to her, I want other women to be safer. I will honour her until I take my last breath."
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Last year she begged people to be alert for lone women on the street.
And in November she revealed how her youngest daughter Beth was almost incoherent after being spiked on a night out.