Pipe bomb suspect Cesar Sayoc made his first appearance in a New York federal court Tuesday and was told he will be held without bond.
The defense issued no objection to Judge Robert Lehrburger's decision. Sayoc's preliminary hearing was set for Monday.
In a letter, prosecutors had said they would ask that Sayoc be held without bond, based on the flight risk and the danger he allegedly posed to the community.
The 56-year-old faces five federal charges: interstate transportation of an explosive, illegal mailing of explosives, threats against former presidents and other persons, threatening interstate communications and assaulting current and former federal officers.
Sayoc's attorney, Daniel Aaronson, has said that his client intends to later plead not guilty to the crimes.
"Nobody has been able in a court of law to say that those were bombs that he sent," the attorney said. "Therefore, there is no reason why he should speak or possibly have any information to impart."
16th explosive device recovered, prosecutors say
Sayoc is accused of sending at least 16 mail bombs to several targets, including CNN, former President Barack Obama and former Secretary of State Hillary Clinton. None of the devices detonated, and no one was injured.
If convicted, he could receive up to 48 years in prison.
Since Sayoc's October 26 arrest, authorities have recovered two more packages containing explosive devices.
The latest package was found Friday, federal prosecutors said in the letter to Lehrburger. The device was in a package addressed to Democratic donor and billionaire Thomas Steyer, in California, prosecutors said. It was the second package Sayoc allegedly mailed to Steyer.
"The defendant used mailing materials nearly identical to the other 15 packages, including the same type of envelope, address format, and stamps," the prosecutors' letter reads.
On Monday, his mother wrote an open letter to television network ABC, in which she warned politicians that fiery rhetoric targeting politicians and journalists resonated with the mentally ill, spurring them to "violently act out in our country."
Madeline Sayoc said her estranged son was mentally ill and that his family tried to get him help over the years, to no avail. She called for stronger laws that would allow American families to "compel and require" treatment for their loved ones, when necessary.
FBI finds target list, package labels
Sayoc was arrested at an AutoZone parking lot in Plantation, Florida, as he neared his white Dodge van, which was plastered with pro-Trump and anti-Democrat memes .
In the week since his arrest, authorities have called the pipe bombs a "domestic terrorist attack."
A letter sent to the judge presiding over Sayoc's case in Florida suggests investigators believe he had planned to continue his alleged attacks.
"Put simply, only the defendant's arrest and incapacitation resulting from his detention were sufficient to stop his attack," U.S. Attorney Geoffrey Berman of the Southern District of New York wrote.
Searches into Sayoc's laptop and cell phone showed he had been doing research online about the homes and families of the recipients of the packages. He also kept a list of their physical addresses and had lists of other potential targets, the letter said.
And while the exact content of the packages has not been discussed in detail, prosecutors said the bombs had clear similarities. They were found in envelopes that had return labels listing the address and the name of U.S. Rep. Debbie Wasserman Schultz of Florida, a former Democratic National Committee chair.
The return labels all had the same misspellings, the letter said.