Teachers have been urged to warn pupils against the dangers of sextortion, a form of blackmail involving threats that intimate pictures will be shared.

The National Crime Agency (NCA) sent an alert to teachers on Monday after cases doubled worldwide in the last year.

Ros Dowey’s son Murray died by suicide after he was tricked into sending compromising pictures by criminals posing as a girl online.

“They’ve totally destroyed our family,” Mrs Dowey told the BBC.

She described her 16-year-old son as a lovely boy, who had the “best sense of humour in our family”.

Sextortion often involves victims being sent a nude picture before being invited to send their own in return – only to then receive threats that the image will be shared publicly unless they meet the blackmailer’s demands.

All age groups and genders are being targeted, the NCA said, but male victims aged between 14 and 18 make up a large proportion of cases.

The NCA said the alert, sent to hundreds of thousands of education professionals, is designed to guide teachers as they support young people who may be targeted.

In an interview with the BBC, Mrs Dowey said her son had gone to his room after a normal family day in their home in Dunblane, Scotland, in December last year.

They had dinner, watched TV and chatted as usual. Murray went to his room “completely happy, completely normal”, but “then the next morning he was dead”.

James Babbage, the director general for threats at the NCA, described sextortion as a “callous crime”.

On Monday, Mr Babbage urged education professionals to help the NCA raise awareness of this type of crime, “which is sadly increasing across the world”.

In its guidance, the NCA aims to “take away the stigma” surrounding sextortion, and prepare teachers to discuss with parents and carers how they should talk to their child about it.

The NCA’s decision to identify this form of blackmail as a “real threat to our young people” was described by Murray’s mother, Mrs Dowey, as a “really positive move”.

As reported by the NCA, 91% of cases dealt with by the Internet Watch Foundation (IWF) in 2023 concerned male victims.

Between 2022 and 2023 the number of reported cases worldwide jumped from 10,731 to 26,718, according to the US National Center for Missing and Exploited Children.

In its report, the NCA said sextortion cases are carried out by organised crime groups based abroad – “predominantly in some West African countries, but some are also known to be located in South East Asia”.

“A lot of victims feel responsible but we need them to know this is absolutely not the case; you are not to blame and help and support is available,” Mr Babbage added in a statement.

He hopes the alert will help raise awareness and encourage young people to report incidents to an adult they trust, the police, or the Child Exploitation and Online Protection safety centre.

In its guidance to parents and carers, the NCA said they should not pay, they should stop contact and block whoever is harassing their child. But it warned parents against deleting anything, as it could be used as evidence.

In a message to those who might be in a similar situation to her son, Mrs Dowey said: “Please don’t do what Murray did. Nothing is worth taking your own life. Nothing.”

“No matter how terrified and awful you’re feeling at the moment, that will pass and this can be fixed,” she added.

If you have been affected by the issues in this story, help and support is available via the BBC Action Line.