Police investigating the disappearance of Nicola Bulley have warned members of the public not to "take the law into their own hands".
Officers have said they will not tolerate" people committing criminal offences by breaking into empty or derelict riverside properties to try to find Nicola who disappeared 11 days ago.
The mum-of-two went missing around 9.20am on Friday, January 27, after dropping her children off at school in St Michael's on Wyre, Lancashire. Her dog Willow was found near the river where officers have been focusing their search.
In a press conference on Tuesday, Lancashire Constabulary warned members of the public not to "take the law into their own hands" and not to direct online abuse at people connected to the investigation.
Superintendent Sally Riley said: "We will not tolerate online abuse of anyone, including innocent witnesses, members of the family and friends, of local businesses, or of criminal damage or burglary. We will be taking a strong line on that, as you would expect."
She told reporters: "There are some properties along the riverside which are empty or derelict.
"Whilst it may be well intentioned that people think that that could be a line of inquiry, I would ask them to desist from doing that.
"In some cases it may be criminal if they are breaking in and causing damage or committing a burglary."
Supt Riley said officers have searched derelict riverside properties with the permission of owners.
"Because there is no criminal element yet identified, and we don't expect there to be in this inquiry, then we're not starting to go into houses because that's not where the inquiry is leading us," she added.
Supt Riley also urged the public to avoid "distressing" speculation about what might have happened to Nicola.
"We would ask that people in the wider community, particularly on social media and online, do not speculate as to what may have happened to Nicola," she told reporters at the press conference.
"This is particularly hurtful to her family, to her children, to her partner Paul, to her parents, her sister and her friends because it is not helpful to them, it is distressing and it is distracting for the police inquiry.
"Nor is it helpful if people, particularly if they have come from outside of the area, take it upon themselves to take the law into their own hands by trying to, for example, break into empty property.
"They may mean well, they may want to help. But they can help in thinking back if they were in the area to what information they may have of relevance to the police and holding the family in their thoughts."
Peter Faulding, leader of underwater search experts Specialist Group International (SGI), has been searching the river for two days after being called in by the family to help.
He has said if his team does not find her in the water using his sonar equipment then he believes she has not been in the river and raised "third party" involvement in the disappearance.
But Supt Riley told reporters at a press conference in the village that Mr Faulding is not included in "all the investigation detail".
She added: "Our search has not found Nicola in the river and then a re-search in parts by SGI has found the same. That does not mean... that Nicola has not been in the river.
"In the light of other inquiries being discounted from the investigation so far... clearly our main belief is that Nicola did fall into the river.
"Clearly Mr Faulding isn't included within all the investigation detail any more than the members of the public are that I'm briefing through these sorts of press conferences."
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