A music teacher who preyed on young boys was told today he would serve a minimum of five years in jail.
Andrew Kingsley, 23, of Alloa, also faces a lifelong restriction order after admitting a "predatory campaign" of sexual abuse against children as young as 12 between 2007 and 2009.
At the High Court in Edinburgh, Kingsley was jailed for at least five years after pleading guilty last year to 31 charges, including using internet chatrooms to groom under-age boys for sex.
Judge Lord Pentland said the worst aspect of Kingsley's "sustained criminality" was the "devious manipulation and relentless pursuit" of his victims for his own gratification.
Lord Pentland told Kingsley the lifelong restriction order meant he would be subject to risk assessment and close supervision for the rest of his life.
He said: "The intensity of your offending, its duration and the level of planning and calculation involved all support this view.
"In my opinion, if you are at liberty there is a likelihood that you will seriously endanger the wellbeing of members of the public at large."
Sixteen boys were targeted by Kingsley, who he begged for sex over the internet.
He committed a serious sexual offence with a 15-year-old boy and engaged in sex acts with two others.
He arranged meetings with some of the other victims, who he sent sexually explicit messages to online or by mobile phone, but they failed to show up.
Kingsley's conviction follows one of the largest investigations into internet offences ever undertaken by Fife Constabulary.
The force's Operation Solus involved a dedicated team which uncovered more than 3,400 chat logs from Kingsley's computers, many of a very sexually explicit nature.
A number of photographs and pornographic videos were seized along with his mobile phone which revealed text messages containing sexual chat.Reuse content