Sayoc faces almost 50 years in prison if convicted on five federal charges that were filed in NY because some of the devices were recovered there.
In support of that argument, assistant prosecutors to Manhattan U.S. Attorney Geoffrey Berman confirmed the November 2 discovery of a 16th explosive device, the second that Sayoc allegedly mailed to Thomas Steyer, the California-based billionaire hedge fund manager and philanthropist who has criticized Trump.
Prosecutors say the most recent crude bomb was recovered last Friday in California, addressed to liberal activist Tom Steyer.
Madeline Sayoc, in a letter sent by her attorney to ABC News, described being "shocked" and "confused" when she awoke from surgery last week and was told her 56-year-old son was accused of the attacks.
His lawyers decided not to seek his release on bail after prosecutors released a letter outlining more evidence against him, including DNA linking him to 10 of the explosive devices and fingerprints on two of them.
Sayoc also searched online for addresses and photos of some of the people sent bombs, including former president Mr Obama, former secretary of state Mrs Clinton and former vice president Joe Biden, it is alleged. His attorneys had said last week in Miami that it would be better if his lawyers in NY could take the case as soon as possible.
Cesar Sayoc's attorneys have not commented on their client's mental health.
None of the devices exploded and no one was injured.
The attempted bombings heightened political tensions and put the United States on edge ahead of Tuesday's midterm elections, seen as a referendum on the Trump presidency.
Authorities arrested Cesar Sayoc, a staunch Trump supporter, in Plantation, Florida, on October 26 in connection with the series of mail bombs ― none of which detonated.
A judge in NY on Tuesday ordered Cesar Sayoc held on mail-bomb charges.
At the time of his arrest, Sayoc was living in his van, which was covered with images supportive of Trump and critical of top Democrats and CNN.