Sextortion scheme
Ryan J Vallee pleaded guilty in 2016 to a 31-count indictment iStock

A US-man has been sentenced to eight years in prison for a sick 'sextortion scheme' that involved hacking into the social media, email and online shopping accounts of over a dozen teenage girls and coercing them into sending him sexually explicit images.

Ryan J Vallee, 23, admitted that between 2011 and March 2016, he used a number of online aliases including "Seth Williams" and "James McRow" to contact his victims – some of whom he knew personally – before threatening them with sexual blackmail.

According to the US Department of Justice (DoJ), he used a number of tactics to make his young victims cave to his demands. In one instance, he hacked into a target's Amazon account and ordered "items of a sexual nature" to be shipped to her home.

In another example, Vallee obtained sexually explicit photos of a victim before then sending them to their friends and family members. In his plea agreement, he admitted to repeatedly sending threatening text messages to the teenage girls.

"If you don't want me to set that as your profile picture on Facebook take your bra off. You have 15 minutes," he wrote in one text message in August 2012, according to court filings.

He continued: "I hacked your Facebook if you don't show me your t*ts I will set this as your profile picture nice p***y too girl. You don't have a choice. If I don't see your tits by ten everyone will see your p***y. Don't make me do this [victim's first name]. I hacked you once I can hack you again."

With at least one victim, the DoJ said he created a Facebook page using an account name that was virtually identical to the victim's real name, posted sexual images of them online and then sent "friend requests" to the victim, her friends and her family members.

According to the admissions in the plea agreement, when most of the victims refused to comply with his demands and begged him to leave them alone, Vallee then sent threats to "inflict additional harm." The names of the victims have been withheld to protect their privacy.

Vallee pleaded guilty in 2016 to a 31-count indictment charging him with 13 counts of making threats, one count of computer hacking to steal information, eight counts of computer hacking to extort, eight counts of aggravated identity theft and one count of cyberstalking.

"Predators troll the internet in search of vulnerable children to extort for their own sexual gratification," said assistant attorney General Leslie Caldwell when Vallee was first charged.

"The criminal division and our law enforcement partners are committed to protecting our youth from sextortion and to finding and prosecuting wrongdoers lurking in the shadows of the internet."

Do you need help with sextortion? See advice on the National Crime Agency (NCA) website here.