Det Ch Insp Peter Carr said the force had "new and significant" lines of inquiry.
“There
are people who know what happened to Vicky, or maybe have information or things
that they know are linked to her death but have not come forward," he said.
In a statement, her family said the young woman "did not deserve to have her life taken",
“We
feel the loss of Vicky every day, she deserves justice and hope that this
reinvestigation puts those responsible behind bars," they added.
Four people have been arrested in connection with Vicky’s murder since 2000, but all have been released with no further action.
Live Reporting
All times stated are UK
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Catch upNewcastle vigil to remember murdered teacher
A candle-lit vigil is due to take place in Newcastle in memory of Sabina Nessa, who was found dead in London last weekend.
The vigil is being held at Grey's Monument at 19:00 BST in memory of the 28-year-old primary school teacher.
Her body was found in a park in south-east London on Saturday.
The Metropolitan Police said a 38-year-old man had been arrested on suspicion of the murder of Ms Nessa.
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Vicky Glass murder: Police reopen historic case
Police are to reinvestigate the murder of a woman who was discovered in a stream in a North Yorkshire village exactly 21 years ago.
Vicky Glass, from Middlesbrough, was last seen being dropped off by a taxi driver in the early hours of 24 September 2000.
Her body was found over a month later in Danby, 13 miles from Whitby on the North York Moors.
Cleveland Police said a new team was formed to actively reinvestigate her death using new forensic techniques, as well as reviewing CCTV images.
In 2018, Cleveland Police's Historic Investigation Unit was given additional funding by the Home Office to reinvestigate the case.
Det Ch Insp Peter Carr said the force had "new and significant" lines of inquiry.
“There are people who know what happened to Vicky, or maybe have information or things that they know are linked to her death but have not come forward," he said.
In a statement, her family said the young woman "did not deserve to have her life taken",
“We feel the loss of Vicky every day, she deserves justice and hope that this reinvestigation puts those responsible behind bars," they added.
Four people have been arrested in connection with Vicky’s murder since 2000, but all have been released with no further action.
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Police to reinvestigate 21-year-old murder
Vicky Glass's body was found six weeks after she disappeared in 2000, but no-one has been caught.
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