BEVERLY — On Feb. 12, Vanessa Trump opened an envelope addressed to her husband, Donald Trump Jr., in their apartment in Manhattan. When white powder spilled out, Vanessa Trump had to be taken to the hospital as a precaution.

More than two weeks later, about a dozen unmarked vehicles descended on a home on a quiet cul-de-sac in Beverly’s Centerville neighborhood.

The startling raid by the FBI’s Boston-based anti-terrorism task force on Thursday morning capped an investigation that led to the arrest of Daniel Frisiello at 7:55 a.m., as he left his home for work. Frisiello, 24, of 62 Hathaway Ave., was charged with five counts of mailing a threat to injure a person and five counts of false information and hoaxes.

Frisiello’s face was expressionless as he was led in shackles and handcuffs into the courtroom at the federal district courthouse in Worcester Thursday afternoon. The pockets on his pants were still inside out.

His parents, who declined to speak to reporters, sat about 20 feet away.

No plea was entered at the initial appearance, where Magistrate David Hennessey advised Frisiello of his rights and the potential penalties he’s facing: Up to 10 years in prison for the mailed threats toward a federal prosecutor and a senator, up to five years in prison for the threats to three others (including Trump Jr.), and a total of 25 years on the five hoax counts.

Scott Gleason, Frisiello’s lawyer, said later that his client will plead not guilty to the charges.

“He’s a good young man from a wonderful family, who has had some difficulties,” said Gleason, a Haverhill attorney hired by the family to represent Frisiello. “We will be talking about those difficulties Monday afternoon.”

Prosecutor Scott Garland of the U.S. Attorney’s anti-terrorism unit filed a motion to detain Frisiello as both a danger to the public and a risk of obstructing justice or threatening witnesses. A hearing on that motion will be held on Monday afternoon.

Gleason asked the judge to note on paperwork that will accompany Frisiello to the federal Wyatt Detention Facility in Rhode Island that his client is on psychiatric medications and had expressed suicidal ideas.

According to an affidavit by U.S. Postal Inspector Michael Connelly, investigators used a variety of techniques to identify Frisiello as the sender of letter and track him down at his Beverly home, including going through his trash and observing him from a camera installed on a pole on his street.

“This investigation should remind people that law enforcement will prioritize finding and charging those who try to cause panic by sending threatening letters containing what looks like dangerous substances,” said U.S. Attorney for Massachusetts Andrew Lelling, during a press conference announcing Frisiello’s arrest.

Donald Trump Jr. — the son of President Donald Trump — reacted to the news of Frisiello’s arrest on Twitter, saying he and his family were “incredibly relieved to hear this news.”

“No one should ever have to deal with this kind of sickening behavior,” he wrote. “Truly amazing work from the @SecretService and other agencies involved. Thank you all for your dedication to law and order.”

Authorities said Frisiello mailed letters with suspicious white powder to Trump Jr. and four others: interim U.S. Attorney Nicola Hanna of California, Stanford Law School professor Michele Dauber, U.S. Sen. Deborah Stabenow of Michigan, and actor and congressional candidate Antonio Sabato Jr. of California.

The letters, sent between Feb. 5 and Feb. 12, contained insulting and threatening remarks, including calling the younger Trump “an awful, awful person,” and stating, “This is the reason why people hate you, so you are getting what you deserve.”

In the other letters, Frisiello gave various reasons for targeting each victim. Hanna, he said, was responsible for the suicide of former “Glee” star Mark Salling, whom she had indicted on charges of child pornography. “I hope you end up in the same place as Salling,” Frisiello wrote.

He criticized Dauber for her efforts to recall a judge who had sentenced a Stanford University athlete who was convicted of sexual assault, to only six months in jail.

In Stabenow’s case, Frisiello targeted the senator because he said she condoned an attempted courtroom attack on USA gymnastics team doctor Larry Nassar by a father. In his letter to Sabato Jr., Frisiello attacked him with a religious slur.

In his affidavit, Connelly said the five envelopes had several things in common. They were all postmarked in Boston. They all had the same type of American flag stamp. None had a return address. And all had typewritten or computer-written messages in addition to the unknown powdered substance.

The powder has since been determined not to be hazardous, but in each instance required hazardous material responses by law enforcement.

Investigators eventually connected the five letters to Frisiello through examination of another mailing — a “glitter bomb” that had been sent to Dauber. Investigators said glitter bombs are a common prank in which someone sends a letter or a box that when opened spills glitter onto the unsuspecting recipient.

Dauber, the Stanford professor, posted on her Twitter account that she had received an “apparent rape/threat glitter bomb.” Investigators contacted the owner of the company that sent the mailing, called shipyourenemiesglitter.com. The owner identified the person who ordered the glitter bomb as Daniel Frisiello.

The owner also told investigators that Frisiello had attempted to use the company to send other glitter bombs, including to members of President Trump’s family. The owner said he did not fulfill those orders because the messages were inappropriate or threatening.

Investigators traced the transaction for the glitter bomb to a credit card owned by Frisiello, and used Registry of Motor Vehicle records and other databases to find his address in Beverly, where he lived with his family.

Connelly said investigators then used “pole camera footage” to watch Frisiello’s house every day from Feb. 17 to Wednesday of this week. Connelly said they observed a person “who appeared to be Daniel Frisiello” leaving or returning from his home every day.

Investigators also monitored his Facebook account, which had several posts mentioning his five victims, including a TV account of the breaking news regarding the white powder sent to Donald Trump Jr. And they viewed surveillance video at a CVS store in Beverly where Frisiello was seen buying bubble mailing envelopes and greeting cards that appeared the match those sent to his victims.

On the night of Feb. 21 and the morning of Feb. 22, investigators conducting surveillance of Frisiello’s home watched people in the house bringing trash and recycling to the street for collection, Connelly said. At 8:20 a.m., investigators “surreptitiously” collected the trash and recycling and brought it to a law enforcement facility to inspect for potential evidence.

Connelly said investigators found an 8 1/2-by-11 piece of paper that appeared to contain remnants of the cut-out messages that Frisiello allegedly sent to the victims, as well as receipts for stamps and packing tape that matched the ones used by Frisiello.

The investigation was led by the FBI Boston Division’s Joint Terrorism Task Force, which included the FBI, U.S. Postal Inspection Service, U.S. Secret Service, and the Beverly Police Department.

Staff writers Julie Manganis and Christian M. Wade contributed to this report. Materials from the Associated Press were also used in this report.

Staff writer Paul Leighton can be reached at 978-338-2675 or pleighton@salemnews.com.