Daniel Mohan has been missing from his Enniskillen home for a week
The mother of a teenager who's been missing from his home in Enniskillen for a week says she "fears the worst".
A search for 16-year-old Daniel Mohan is currently focused on Lough Erne, part of which is being dragged.
Daniel, who suffers from an attention deficit disorder, was due to go to a friend's house but never turned up.
His mother Tracy McMulkin told the BBC that her son had recently begun to take the drug mephedrone and that his mood had subsequently changed because of it.
She said: "He turned right round. He was much more quiet than he ever was. He would have tinkered about with old cars and motorbikes and stuff - he lost all interest in that.
"Now he would just keep up the hood the whole time and sat underneath it hiding. He just changed."
Mrs McMulkin said that she had learned from friends that Daniel had recently begun to take the mephedrone.
Sold as a white powder, capsules and pills or can be dissolved in liquid
Often sold online as plant food marked "not for human consumption"
Completely different to methadone, used to treat heroin addicts
Long-term effect unknown
Also illegal in Israel, Denmark, Norway and Sweden
It was banned earlier this month after being blamed for the deaths of a number of teenagers across the UK.
In Northern Ireland, a number of recent suicides have been reportedly linked to depression caused by misuse of the drug.
However it has not been definitively established as a cause of death.
Mrs McMulkin said that her son's attention deficit disorder made him "vulnerable" and "easily led".
"I knew something had happened him because it wasn't Danny - he was changing, his personality was changing, he was becoming grumpy and you couldn't talk to him," she said.
She added that she fears her son will not be coming home.
"Danny would never stay away from me. Danny would come home," she said.
"They checked all of his accounts. No money has been touched. They checked his mobile phone too and they were unable to put a trace on that."
Mephedrone has been linked to a number of suicides across the UK
Mrs McMulkin has herself been taking part in the search of Lough Erne.
"I looked - I went down into the bank and looked to see if I could find him.
"If he is lying in that cold water, I want him home. I don't care - I just want him back. The longer it goes on, I know he is not coming back to me.
"Our lives are still. People are coming in and out. They're bringing candles and prayers for Danny but it is Danny I want.
"I would just plea with any child - please do not touch drugs, please. You're destroying yourself and you're destroying your home."