The family of a 24-year-old woman whose death police have linked to the party drug mephedrone today paid tribute to a "really lovely girl".
Lois Waters' body was found yesterday at an address in the village of Norton, North Yorkshire.
Detective Chief Inspector Nigel Costello, who is leading the inquiry, said family and friends have told him she had been taking the drug in the 48-hour period leading up to her death, possibly with other substances.
Today her tearful mother, Alison, said the death of her "quiet" daughter was unexpected and that she was a "really lovely girl".
Mrs Waters was visibly emotional as she spoke about her daughter at a family member's home in Norton today,
She said: "Lois was a really lovely girl, she was really quiet. That's all I can really say about her at the moment."
Mrs Waters paid tribute to her daughter as Professor Les Iversen, the Government's chief drugs advisor, indicated that mephedrone was likely to be made a Class B drug.
In evidence to the Home Affairs Committee, Prof Iversen, the chairman of the Advisory Council on the Misuse of Drugs (ACMD), said his personal view was mephedrone was "amphetamines by another name" and that any deaths linked to the drug were a "tragedy".
North Yorkshire Police were waiting for the results of toxicology tests to work out what role, if any, mephedrone played in Miss Waters' death, who was found at the house of a friend yesterday morning.
Mr Costello said police were called to the house, where Miss Waters had been staying since the early hours of Sunday morning, just after 9am on Monday.
The detective said the victim spent Sunday saying she did not feel well, complaining of feeling drowsy and was asleep for most of the day.
He said his officers had been told she had been taking mephedrone over the weekend but he was still trying to work out whether she was at friends' homes or in local pubs.
Mr Costello said other substances had been recovered but he is not yet in a position to say what they are.
Miss Waters' death follows those of Louis Wainwright, 18, and Nicholas Smith, 19, who died in the Scunthorpe area last week following a night out.
The deaths prompted criticism of the Government for not doing more to tackle the threat from mephedrone - also known as M-Cat or Miaow Miaow - which is manufactured as plant fertiliser.
After the Scunthorpe deaths, opposition parties attacked the "inordinate delays" in research into the drug which could have led to it being banned.
It is claimed these delays were related to the fallout from last year's sacking of the chairman of the Advisory Council on the Misuse of Drugs, Professor David Nutt.
Ministers vowed that "immediate action" would be taken on a report into a group of so-called legal highs, including mephedrone, due to be issued at the end of the month.
It is expected that Government drug advisers could recommend a ban on the drug within weeks.
People in Norton said they were shocked at Miss Waters' death.
Deborah Cook, the landlady of the Union Inn and a friend of the family, described Miss Waters' death as "very sad".
Another woman, who did not want to be named, said: "It's such a shock. You don't expect things like this to happen on your doorstep. It's horrible, a real tragedy."
Speaking at a news conference in York earlier today, Mr Costello said Miss Waters was a "normal girl".
The detective warned people to avoid mephedrone and not to believe it is safe just because it is not illegal.
He said: "People think this kind of thing happens to other people in the big cities but this is not always the case."