A 999 call handler downloaded hundreds of indecent images of children after learning about the dark web on a police training course.
Ian Curtis, 47, of Swansea, who worked for South Wales Police for 25 years, admitted downloading images of children as young as five.
He was jailed for 12 months at Swansea Magistrates’ Court.
Judge Geraint Walters said Curtis had built up a “huge library of the gravest images”.
The court heard that among the indecent images were 295 videos of children in the most serious category, as well as 111 still images.
He also admitted downloading extremely pornographic images involving sex acts on animals.
Robin Rouch, prosecuting, said Curtis had learned about the dark web while attending a computer course put on by the force.
Judge Walters said the call operator had gone on to dedicate several years of his life downloading illegal material.
He said: “Given the nature of his work he would have known it was grossly wrong but he thought it was worth risking it all.
“He was dealing with members of the public reporting crimes but in the privacy of his own home he was committing crimes himself.”
The court heard Curtis was suspended following his arrest and will lose his job.
He was also made subject to a sexual harm prevention order, restricting his access to the internet after his release, and will be on the sex offenders’ register for 10 years.
Image copyright South Wales Police