A 24-year-old Massachusetts man is accused of sending a threatening letter containing white powder to Donald Trump Jr.’s New York City apartment, along with mailing threats to four other people around the country, federal prosecutors say.

Daniel Frisiello, of Beverly, was taken into custody Thursday and faces multiple federal charges. The letter containing white powder, which turned out to be harmless, was opened by Trump Jr.’s wife, Vanessa Haydon Trump, on February 12. She was taken to the hospital as a precaution, according to NBC News. The powder was tested and turned out to be corn starch, police sources told NBC News.

Inspector Michael Connelly, of the U.S. Postal Inspection Service, wrote in an affidavit, “Within the past several weeks, at least five locations around the country have received an envelope that bears a Boston postmark on the outside and contains inside a suspicious white powder and a written message indicating or implying that the powder is dangerous or sent to cause the person danger.”

Frisiello was charged with five counts of mailing a threat to injure the person of another and four counts of false information and hoaxes. Frisiello works for Catholic Charities at a child care center and has been placed on leave from that job, the Archdiocese of Boston said in a statement.

“These kinds of hoaxes may not cause physical harm but they scare the heck out of people because most of us recall the Anthrax mailings of the early 2000s, when five people were killed,” U.S. Attorney Andrew E. Lelling said at a press conference. “These hoaxes are easy to pull off – all you need is an envelope, a stamp and a white powdery substance. So you’ll see this office aggressively purse these kinds of cases.”

Here’s what you need to know:

1. Frisiello Also Sent Letters Containing White Powder to a U.S. Attorney, a Stanford Law Professor, a U.S. Senator & a Trump-Supporting Actor Who Is Running for Congress, Prosecutors Say

Along with the letter to Donald Trump Jr., Daniel Frisiello is also accused of sending threatening letters to Nicole Hanna, the interim U.S. Attorney for the Central District of California; Stanford University law professor Michele Dauber; Michigan U.S. Senator Deborah Stabenow; and actor Antonio Sabato Jr., court documents show. The letters also contained white powder, prosecutors say. Hazardous materials teams had to be called after each letter was opened, but all were determined to be harmless.

The letter to Trump Jr. was mailed February 7 in Boston. Along with the white powder, it contained the following text, prosecutors say:

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 deserve. So shut the F*CK UP!

After the incident, Vanessa Trump tweeted she was thankful her family was safe and called it an “incredibly scary situation.” Her husband tweeted, “Truly disgusting that certain individuals choose to express their opposing views with such disturbing behavior.”

Hanna and the Central District of California U.S. Attorney’s office received a letter after the death of “Glee” actor Mark Salling, who was being prosecuted by Hanna’s office on child pornography charges. The letter accuses Hanna of “murdering” Salling and calls for her to “end up in the same place as Salling.” That letter, like the one to Trump Jr., was postmarked February 7 in Boston.

“Mark Salling was an indicted defendant in a child pornography case prosecuted by the U.S. Attorney’s Office for the Central District of California. On or around January 30, 2018, news media reported Salling’s death and by February 1, 2018, news media reported that his death had been ruled a suicide,” Inspector Michael Connelly, of the U.S. Postal Inspection Service, wrote in an affidavit. “In addition to the above message, which appears to blame Mark Salling’s death on the U.S. Attorney’s Office, Envelope 2 also contained an unknown suspicious white powder, which spilled out of the envelope when it was opened.”

Dauber, who is leading the recall effort against California Judge Aaron Persky, who sentenced Brock Turner to six months in jail in the Stanford rape case, received a letter telling her the sender was “going to treat” her “like ‘Emily Doe,'” adding “let’s see what kind of sentence I get for being a rich white male.”

That letter was also mailed in Boston on February 7, and was opened by Dauber’s co-worker on February 14, Connelly said.

Dauber also received a “glitter bomb” that included a rape threat, prosecutors said. “A glitter bomb is a letter containing glitter sent to an unsuspecting individual that, when opened, spills out onto the recipient,” the U.S. Attorney’s Office said. Dauber shared a photo of that letter on Twitter:

Professor Dauber's Mailbag: this is an apparent rape threat/glitter bomb. Creative. @palumboliu pic.twitter.com/hJMvYkhSka — Michele Dauber (@mldauber) February 6, 2018

Stabenow, a Democrat, received the letter during the sentencing of former Olympic gymnastics doctor Larry Nassar, who was convicted of child molestation. That letter was postmarked Ferbaruy 12 in Boston, Connelly said. It was opened on February 15 by a staffer in Stabenow’s East Lansing office, according to Connelly.

The letter criticized Stabenow for supporting Randall Margraves, the father of three of Nassar’s victims, who tried to attack Nassar in court. “If you condone Margraves reaction to his daughter’s testimony on Dr. Nassar, you are no better than he is. You deserve what is coming to you like he is thinking, you’re a c*nt version of a vigilante, do us a favor go suck a c*ck or better yet.”

Stabenow had said that she wished court security was a little slower in restraining Margraves and also said she would like “five minutes” with Nassar herself.

The fifth letter was also postmarked February 12 in Boston and was sent to an unidentified California company that formerly did business with Antonio Sabato Jr., according to court documents.

The letter to Sabato Jr., an avid Trump supporter who is running for Congress in California as a Republican, said, “You’re an awful person I am surprised that the olive skin mouth isn’t orange. Since you think Obama is a practicing Muslim that makes you a filthy kyke. Since kykes like you never change. You and McCain Jr belong together in hell, because that is where you’re going not Christian heaven. You know what your party does with kykes,” prosecutors say.

Connelly said all five letters were postmarked in Boston, all five had the same stamp bearing an American flag and did not have a return address. Three of the mailings appeared to be red greeting-card-style envelopes, while two others appeared to be white greeting-card-style envelopes, Connelly wrote in his affidavit. You an see an example of the envelope below:

Connelly said, “three of the addresses on the outside of the envelopes appear to have been typed or printed onto a white piece of paper that was then affixed to the envelope with clear packing-style tape. The remaining two addresses were written directly on the side of the envelopes,” Connelly wrote. “All five envelopes contained typewritten or computer-written textual messages inside in addition to the unknown powdered substance.”

Connelly said the font, border and style of the text was all similar.

“The messages also appear to have a distinct pattern linking them together in that across all five messages, at several points, the ink used to print the messages is lighter in color than others surrounding it. This leads me to conclude that there may be a technical issue with the device that printed the messages and they all originated from the same machine,” Connelly wrote in the affidavit.

2.A List of His Targets Was Found in the Trash at His Home & Investigators Say He Tried to Send 10 Other ‘Glitter Bombs,’ Including to Trump Family Members

Frisiello lives in Beverly, Massachusetts, with his parents. He was taken into custody March 1 at his home on Hathaway Avenue after an FBI raid, the Salem News reports.

Investigators also learned that Frisiello bought stamps, envelopes, packaging materials and greeting cards at a CVS store in Beverly, according to court documents. He was seen on surveillance video making the purchases in January and February, and they were also connected to his CVS Rewards card, investigators said.

The FBI's Terrorism Task Force raided a Hathaway Ave home in #BeverlyMA this morning. Story via @heardinbeverly. https://t.co/OYCj7NXFsa pic.twitter.com/53sDO740kE — Arianna MacNeill (@SN_AMacNeill) March 1, 2018

According to court documents, federal agents searched the trash outside of Frisiello’s home in Beverly, while conducting surveillance on February 21 and 22. Inside the trash, agents found what appeared to be a typewritten list of Frisiello’s targets. The list had been cut with scissors and was missing parts. “An alt right Hollywood actor running for Congress,” an apparent reference to Sabato, could still be seen. Deborah Stabenow’s name also remained on the page, along with the description, “imbecllic senator who approved how Musgrave handle the situation and wanted it to happen.”

They also located the receipt used to buy the stamps that matched those used on the five envelopes in Frisiello’s trash, according to court documents.

The U.S. Attorney’s Office wrote that, “It was determined that there were notable commonalities among the envelopes, including that all five envelopes contained an unknown powdered substance, which has since been determined to be nonhazardous. … Law enforcement traced financial records to Frisiello who ordered and paid for the glitter bomb to be delivered to Professor Dauber. Furthermore, on Feb. 21, 2018, agents recovered trash from Frisiello’s residence that appeared to contain remnants of the cut-out messages that Frisiello allegedly sent to the victims.”

Inspector Michael Connelly wrote in the affidavit, “Sending an individual a ‘glitter bomb’ is a phenomenon in which someone sends an unsuspecting individual a letter or cardboard mailing tube that, when opened, is revealed to contain glitter that typically spills out and gets onto the individual’s clothes and personal effects. It is a common prank that people play and is readily viewable on youtube.com and social media. This letter was significant because the text of the glitter bomb sent to Professor Dauber matched the text of the white-powder letter sent to Professor Dauber.”

Connelly and other investigators found the glitter bomb was bought using shipyourenemiesglitter.com. Personalized glitter bombs can be bought on that site for $10.98. It is sold as a novelty or practical joke and the website states that it should not be used to “threaten, constitute harassment, violate a legal restraint or any other unlawful purpose.”

The owner of the store told investigators that he was aware of the Dauber glitter bomb and said he did not know who Dauber was or the meaning of the message sent to her when the company mailed it. He told investigators he was remorseful and stated he never intended his service to be used for threatening, harassing or sending sexual messages. The owner provided investigators with information showing the glitter bomb was bought by Frisiello, Connelly said.

“The owner also told law enforcement that Frisiello had attempted to use his company to send over 10 additional glitter bombs to other people, including members of President Trump’s family. The owner knew some of these additional letters were intended to be sent to members of President Trump’s family because the names were all associated with President Trump,” Connelly wrote. “The owner did not fulfill these additional order requests because the messages appeared to be inappropriate and/or threatening.”

You can read the court documents below:

3. Frisiello Works for Catholic Charities at the Peabody Child Care Center & Previously Worked for a Charity That Helps People With Disabilities

According to his Facebook profile, Frisiello, who has shared and commented on several news articles critical of President Donald Trump and Republicans, works as a program assistant at Catholic Charities in the Archdiocese of Boston. According to his Facebook profile, he has worked at Catholic Charities in Peabody since August 2017. The archdiocese said he works at the Peabody Child Care Center and has been placed on leave.

“On Thursday, March 1 Catholic Charities of Boston was contacted at 9:15 am by the FBI concerning their arrest this morning of an individual employed in our Peabody Child Care Center. The employee in question was immediately placed on leave,” Catholic Charities said in a statement. “The FBI has assured us that the charges do not involve any activity in his role at Catholic Charities but concern alleged threats against a political figure.”

Catholic Charities added, “As a matter of background, Catholic Charities processed the appropriate background checks when the employee was hired. We are cooperating fully with the FBI and commend them for their vigilance in immediately contacting and prioritizing the safety of this agency, our employees, and those we serve.”

He previously worked for Northeast ARC, a Danvers-based organization that provides support to people with disabilities, from May 2010 to January 2013. He is graduated from Learning Prep School in West Newton in 2013. He then attended North Shore Community College, where he got an associate’s degree in legal administrative studies in 2016, his Facebook page shows.

Frisiello’s neighbors in Beverly were told by the FBI that there was no threat to the area, the Salem News reports. A warrant for Frisiello’s arrest was signed on February 28 and the raid on his house happened about 8 a.m. the next day.

“I heard a big explosion and then these guys came rolling up,” neighbor Richard Faille told the Salem News.

According to the Salem News, “Several agents wearing protective vests and FBI JTTF (Joint Terrorism Task Force) jackets, as well as members of the FBI Evidence Response Team, were seen going in and out carrying bags and various items, including a laptop computer.”

4. He Posted News Stories About the Threatening Letters & His Targets on His Facebook Profile, the Feds Say

Frisiello posted news stories about the targets of his letters on his Facebook page in February, according to court documents. After the letter to Trump Jr. was opened by Vanessa Trump, Frisiello shared an ABC News story about the incident.

After the letter was sent to the U.S. Attorney’s Office in California, Frisiello shared a story titled, “Mark Salling Dead in Apparent Suicide at 35,” and commented, “What the…..Not again!”

He also shared a post about the incident involving the father of one of Larry Nassar’s victims that included a quote from Stabenow, who had said she wanted “five minutes” with Nassar. Frisiello wrote in a typo-riddled comment, “Good god now the democrats are going off the rails. This is not the democratic means and i am embarrassed to be in the same party as her, because i am not her. I would be offender if anyone i knew in the Democratic party has the dame feelings and thoughts of this imbecile of a senator!”

In his letter to Sabato, investigators say Frisiello wrote, “I am surprised that that olive skin mouth isn’t orange.” According to investigators, “On February 3, 2018, at 1:28 p.m.,” Frisiello “shared a meme that contains a photo of Congressman Devin Nunes with an orange mouth that was captioned ‘MONICA LEWINSKY HAS NOTHING ON DEVIN NUNES.'”

On February 5, Frisiello shared a “meme of a post by ‘Donald Trump Is Not My President,’ which appears to be a picture of Sean Hannity speaking with an orange mouth and the caption ‘I LOVE YOU DONALD!’ on the photo,” investigators said. Frisiello added a comment, “You know you can really see that on the Hannity Report!”

5. Frisiello, Who Is Being ‘Very Cooperative’ With Investigators, Faces Several Years in Prison if Convicted

According to NBC’s Tom Winter, Frisiello is cooperating with investigators. He was set to make his first appearance Thursday afternoon in federal court in Worcester.

NBC News: Frisiello is being interviewed by federal agents right now and is being "very cooperative" Asst. Special Agent in Charge of FBI Boston, Peter Kowenhoven says. — Tom Winter (@Tom_Winter) March 1, 2018

Frisiello faces several years in prison if convicted. According to prosecutors, the charge of mailing a threat to injure the person of another carries a potential sentence of up to five years per count. It can be upgraded to 10 years if the threat is made to a federal official. False information and hoaxes also carries a potential sentence of up to five years in prison per count.

“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,” Massachusetts U.S. Attorney Andrew Lelling said in a statement. “Beyond terrifying the victims, these incidents caused law enforcement agencies around the country to spend time and money deploying emergency response units. Thankfully, the white powder in these letters was inert and no one was harmed. This does not change the fact that the defendant allegedly used the internet, the U.S. Mail, and popular fears of biological weapons to threaten and frighten people who did not share his views, and that is something we will prosecuted accordingly.”

Harold Shaw, the Special Agent in Charge of the FBI’s Boston Division, said in a statement, “This investigation by the Boston Joint Terrorism Task Force sends a strong message to those who seek to terrorize the public by sending powder letters through the mail. Whether real or a hoax, don’t do it. There are plenty of appropriate, lawful ways, to express your opinion and voice your displeasure, but inducing panic and sending what is believed to be a weapon of mass destruction through the mail is certainly not one of them. As alleged, Mr. Frisiello sent letters from the Boston area containing white powder that required emergency responses all over the country. While we determined that the mailings did not contain toxins or poison, each of these incidents required a significant law enforcement response, a field screening of the letter’s contents, and a methodical analysis by FBI weapons of mass destruction and laboratory experts. All this comes at a cost to taxpayers’ money and diverted first responders and other limited resources away from actual emergencies.”