A grandmother from a village near Warminster says she feels embarrassed to be dubbed Wiltshire’s Miss Marple, after tracking down an American man accused of encouraging vulnerable youngsters to commit suicide over the internet.

Self-confessed technophobe Celia Blay, 64, who lives with her husband Tom, 67, in Maiden Bradley, started investigating the man’s activities in 2002, after striking up an online relationship with a depressed teenager.

Despite police and the FBI refusing to investigate the case, Mrs Bray remained determined to unmask the online voyeur, who posed as a woman in her 20s to encourage depressed and suicidal people, mostly teenagers, to commit to a suicide pact. Eventually Mrs Bray managed to convince local police in Minnesota, USA, to take on the case and their inquiries resulted in the arrest of nurse William Melchert-Dinkel, 47, from Minnesota.

Mr Melchert-Dinkel is under investigation in connection with the suicides of Mark Drybrough, 32, who hanged himself at his home in Coventry, England, in 2005, and 18-year-old student, Nadia Kajouji, from Ontario, who drowned in a river in Ottawa in 2008.

Investigators believe he may have contacted more than 100 people across the world and that he was involved with at least five who killed themselves. He has allegedly admitted to American police that he was involved in at least five deaths. He is expected to be charged within weeks.

Mrs Blay admits she remains a novice when it comes to the internet, and had to rely on the help of her son, Paul, to track down Melchert-Dinkel, who was using aliases such as Li Dao and Falcon Girl.

“Without my son I would have got nowhere,” she said.

“He reckons that I’m at about an eight-year-old’s standard now.

“He was obviously phoney and these people weren’t in pacts with the person they thought they were.

“I emailed all those he had been in contact with and asked if they could send me their chat logs so I could give them to the police and all but one said OK.

“There were about 30 people involved at that stage, in 2006.

“Other people I know he has been in contact with have subsequently committed suicide.”

The mother-of-two and grandmother-of-one tried for years to convince police to take on the case. When she took her evidence to police in Birmingham, an officer phoned her husband.

Mr Blay said: “They called me and said ‘are you Tom Blay?’ and I said ‘yes’. Then they said ‘do you know where your wife is and what she’s doing?’, so I backed her up completely.

“They were checking up on her because they probably thought she was a nutter.”

It was through her work as a carriage whip maker that Mrs Blay had her major breakthrough. One of her customers in Minnesota knew a member of staff at the sheriff’s office in St Paul’s and they agreed to investigate the case.

Mrs Blay said: “This guy has been active since at least 2002, because I met a girl who was a student in the UK and he told her which tablets to take to overdose,” she said.

“She was in a coma for a week but recovered. He knew exactly what he was doing.

“He never offered any alternative other than suicide. He obviously has a fascination with death. Everyone keeps saying to me that a professional investigator should be doing this, but I just couldn’t turn my back on this.”