BOSTON (CBS) — A 40-year-old U.K. citizen who most recently lived in Worcester has pleaded guilty to soliciting the kidnapping of a child as well as distribution and possession of child pornography, according to a prepared statement from U.S. Attorney Carmen M. Ortiz’s office.

Geoffrey Portway had a dungeon in his basement where he planned to sexually abuse, murder and cannibalize a child, the U.S. attorney’s office said.

As part of his guilty plea, Portway has agreed to serve 18 to 27 years in prison, register as a Level 3 sex offender and accept deportation after his incarceration, according to the deal filed Monday in U.S. District Court in Boston.

On July 27, 2012, federal agents along with state and local police, executed a federal search warrant at Portway’s Worcester home. Computers and digital devices containing his child pornography collection were seized, as well as the computer he used to trade child photography and attempt to plan the kidnapping of a child.

During the search of Portway’s basement, investigators found “a dungeon, which was lined with acoustical sounddeadening material and contained a chair, television, and what appeared to be cable access to the Internet,” the U.S. attorney’s prepared statement says. “The room also contained a child-sized homemade coffin (with large speakers covered in wire mesh at one end) with exterior locking devices, a steel cage (approximately 3 feet wide, 2 feet high and 4 feet long) with multiple locking devices, and a steel table top (with steel rings at six points, presumably for restraints). Outside these rooms were a cabinet freezer, an upright freezer, disposable scalpels, butchering kits, and castration tools.”

The dungeon was intended for kidnapped children, according to the U.S. attorney: “This dungeon was described in detail by Portway in recovered (online) chats as a place he intended to use to keep kidnapped children while he sexually abused them and as a place to eventually murder and cannibalize the children.”

Investigators found a wealth of evidence on the U.K. native’s computers.

“Portway engaged in numerous (online) chats with many individuals about a mutual interest in abducting, raping, murdering, and eating children,” the U.S. attorney’s prepared statement says. “Many of these conversations were accompanied by the trading of child pornography. These chats also included images of children known to them, accompanied by discussions of the desire to sexually abuse, murder and cannibalize those children.”

The U.S. attorney said a Kansas man was among the people Portway enlisted online to to help kidnap a child: “Portway solicited several people for their help in abducting a child, predominately from Michael Arnett of Kansas. At least as early as 2010, Portway utilized Skype and other programs to communicate with Arnett, trading child pornography including images of injured, mutilated and deceased children while chatting about the sexual abuse, rape, abduction, murder, and cannibalism of children. Over months, Portway repeatedly solicited Arnett to kidnap a child for him, with the intent that Portway would ultimately rape, kill and eat that child.”

Arnett has pleaded guilty in Kansas to the sexual exploitation of a child to produce pornography.

The investigation began in Milford in 2010, then expanded to Europe and other countries, according to Bruce Foucart, special agent in charge of Homeland Security Investigations in Boston. “Thanks to the determination of HSI, along with our partners at the U.S. attorney’s office, we have been able to rescue 160 children and arrest 51 perpetrators worldwide,” Foucart said in the prepared statement from Ortiz’s office.