A man accused of putting devices resembling pipe bombs on high-voltage power lines left a note threatening to attack utilities and to publish online instructions on how to make similar devices, according to an FBI affidavit released Monday.

Danny Kelly was arrested Saturday, days after firefighters responded to a brush fire near National Grid electric power lines in Tyngsborough, 35 miles northwest of Boston.

Authorities said they found metallic, cylindrical devices hanging from the power lines. One of the devices was found on the ground and is believed to have started the brush fire.

An FBI affidavit says Kelly, of nearby Chelmsford, was charged more than a decade ago with cutting about 18 telephone and cable lines and threatening to cut more unless he received payment. He pleaded guilty to extortion in that case.

Kelly made a brief initial appearance in court Monday on a charge of attempting to maliciously damage and destroy property used in interstate and foreign commerce and in an activity affecting interstate and foreign commerce by means of fire. Assistant U.S. Attorney Aloke Chakravarty said the crime is designated as a federal crime of terrorism and carries a prison sentence of five to 20 years upon conviction.

Kelly, 61, will be held in federal custody pending a detention hearing scheduled for Thursday.  He did not enter a plea Monday. His attorney, assistant federal public defender Joshua Hanye, declined to comment.

The affidavit says Kelly left a note in Tyngsborough saying he was going to war and threatening attacks on critical infrastructure. The note rails against the U.S. attorney's office and the FBI, calling them "lying, bottom feeding, and corrupt organizations." It cites damage "Courts have done to my family, in their goal to punish me for standing up for my rights."

In the affidavit, FBI special agent Scott McGaunn said that during his 2005 prosecution Kelly told the FBI he was very familiar with electric wires and could easily take out the power to Boston, the state's capital and its largest city.

During another interview, Kelly said he had sought the FBI's help for a case against his former employer, and he complained he had lost his home and his family had been destroyed, authorities said.

Kelly also has filed more than a dozen lawsuits, including one against his hometown, complaining about its nativity scene, which he viewed as an affront to his family, the FBI said.

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