A man is due to be sentenced later this month after admitting to possessing a paedophile manual.
Callum Leeder was arrested on May 15 at an address in Chelmsford following an investigation by the Police Online Investigation Team (POLIT) into allegations of indecent images of children.
Leeder, 28, of Rubensgate, Chelmsford, was later charged with possession of a paedophile manual.
Appearing before Basildon Crown Court on June 12 he admitted the charge and is due to be sentenced on June 30.
Detective Inspector Jo Collins, who leads POLIT, said: “This is an unusual and very serious case and deeply concerning that a paedophile’s manual has been found.
“Callum Leeder is clearly a danger to children and I’m pleased the work of my team has led to this conviction.
“By ensuring this manual cannot now be distributed to other predators we have been able to protect children.”