A man has been arrested and charged with sending letters with white powder to five people, including one to Donald Trump Jr. that landed his wife, Vanessa, in hospital. (The couple is pictured below.)
Daniel Frisiello, of Massachusetts, is accused of mailing five envelopes earlier this month with threatening messages and a white substance, which turned out to be non-hazardous.
He was held during an appearance in US federal court in Worcester on Thursday pending a detention hearing scheduled for Monday.
Frisiello showed no emotion as he was led into court wearing a red polo shirt with his hands cuffed and ankles shackled. A prosecutor said family members told them Frisiello may be on medications for suicidal thoughts.
"These kind of hoaxes may not cause physical harm, but they scare the heck out of people," said Andrew Lelling, US lawyer for Massachusetts.
Hoax attacks using white powder play on fears that date to 2001, when letters containing deadly anthrax were mailed to news organisations and the offices of two US senators. Those letters killed five people.
Authorities say Frisiello sent five envelopes early last month that included threatening messages often containing profanities and white substances. The envelopes were postmarked in Boston.
Federal authorities said one of the letters containing powder was sent to Antonio Sabato Jr, the Republican former underwear model and soap opera actor who is running for a US House seat in California.
Other recipients were Debbie Stabenow, the Democratic US senator from Michigan; Nicola Hanna, an interim US lawyer in California; and Michele Dauber, a Stanford University law professor who has promoted the effort to recall the judge who presided over the Brock Turner sexual assault case.
The letter to the president's son was opened by Vanessa Trump on February 12. She called 911 and reported she was coughing and felt nauseous. She was taken to hospital briefly.
The substance in the letter turned out to be cornstarch.
The envelope sent to Mr Trump junior included a typed message calling him an "awful, awful person", according to court documents.
"I am surprised that your father lets you speak on TV," the message said. "You make the family idiot, Eric, look smart."