PLYMOUTH, Mass. (AP) — Federal authorities say they found several guns and a handwritten journal entitled ‘‘Mass Murder Book’’ in the home of a child pornography suspect from Plymouth.

Brendan Kessler made an initial appearance in U.S. District Court in Boston on Tuesday, and is being held for a detention hearing Thursday.

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Prosecutors say the 24-year-old Kessler had been under investigation and a raid of his home and allegedly turned up child pornography on computers and electronic devices.

In addition, authorities found three handguns, three shotguns, eight rifles, detonator cords, remote firing switches and other items. The journal contained ‘‘detailed entries describing steps to be taken in an assault,’’ authorities said.

A public defender for Kessler says the weapons did not belong to his client, but to someone else who lived in the home.