JACKSONVILLE, Fla. -- A 57-year-old Jacksonville Beach man pleaded guilty to receiving child pornography over the Internet and has agreed to forfeiture his home where he downloaded and collected the pornography, the State Attorney's Office said Friday.

William McCarthy faces at least five years and up to 20 years in federal prison and will be required to register as a sex offender.

According to court documents, the Jacksonville Sheriff's Office and U.S. Immigration and Customs Enforcement conducted a search for individuals who were trading images of child pornography using a particular Internet file sharing program. They traced a file of child pornography available for downloading or "sharing" to a particular Internet protocol address that was registered to McCarthy at his Jacksonville Beach home.

On Feb. 4, 2009, law enforcement agents executed a federal search warrant at McCarthy's residence, and McCarthy admitted having downloaded sexually explicit images of children, according to documents. McCarthy denied having any "desire to go pursue kids," but said that he found the child pornography images "different," "not allowed," and "exciting."

According to documents, McCarthy said that he had been using the targeted file sharing program to download child pornography for several years and that he probably had been looking at child pornography for about four years. He said that he had viewed images with children as young as "in diapers."

Agents seized several computer systems from McCarthy's residence that McCarthy had built to enhance the computers' memory and capacity, prosecutors said. McCarthy's computers contained approximately 60,875 images and 649 videos depicting child pornography.

Prosecutors said analysis showed that McCarthy had downloaded numerous images and videos from the Internet using Internet file sharing programs. Several of the images and videos of child pornography that McCarthy received and possessed portray sadistic conduct, prosecutors said.