WASHINGTON (WASHINGTON POST) - A Massachusetts man is accused of sending numerous envelopes containing "suspicious white powder" and threatening messages to Donald Trump Jr and other public figures, federal authorities said.

One letter, sent last month to New York, was addressed to "DonalD trump Jr," officials said.

It read: "You are an awful, awful person, I am surprised that your father lets you speak on TV. You make the family idiot, Eric, look smart. This is the reason why people hate you, so you are getting what you deserved. So shut the f- up," according to a criminal complaint.

The envelope was filled with a white powder that spilled out "onto the addressee's wife," the complaint said.

FBI assistant special agent in charge Peter Kowenhoven told reporters in Boston on Thursday (March 1) that federal authorities had taken 24-year-old Daniel Frisiello into custody "without incident."

The suspect, from Beverly, Massachusetts, has been charged with five counts of mailing threatening communications and false information and hoaxes, according to the complaint.

He is scheduled to appear on Thursday in US District Court in Worcester, Massachusetts.

Police in New York said last month that a letter containing "an unidentified substance" was mailed to Donald Trump Jr's home, and that it was opened by his wife, Vanessa.

She was taken to a hospital as a result, but Trump Jr - the President's oldest son - later said that his wife and children were "safe and unharmed."

He also suggested at the time that the letter may have been motivated by political rancor, writing on Twitter that it was "disgusting that certain individuals choose to express their opposing views with such disturbing behaviour."

Testing determined that the powder in the envelope was "nonhazardous", the complaint said.

Frisiello is also accused of sending threatening letters and powder to Democratic Senatior Debbie Stabenow; a Stanford law professor; a federal prosecutor; and soap star-turned-congressional-aspirant Antonio Sabato.

The Daily News of Newburyport reported that the FBI's Joint Terrorism Task Force searched Frisiello's home on Thursday morning.

FBI spokeswoman Kristen Setera told the newspaper that the raid was a "court-authorised activity in connection with an ongoing federal investigation."

A neighbour, Richard Faille, told the newspaper that FBI agents in protective vests and jackets marked "JTTF" swarmed the house on Hathaway Avenue in Beverly, Massachusetts.

"I heard a big explosion and then these guys came rolling up," Faille told the newspaper.