MIAMI — Even as the Florida bombing suspect appeared in court on Monday in connection with more than a dozen explosive devices sent to critics of President Trump, an additional threatening package addressed to CNN was recovered and investigators said that the suspect had prepared a list of about 100 possible targets.

The federal authorities did not publicly name the individuals and news organizations on the list that they believe the suspect, Cesar Sayoc Jr., compiled before his arrest on Friday, but law enforcement officials have begun notifying people who appeared on it. The list and the package recovered on Monday suggested that the national turmoil that Mr. Sayoc is accused of unleashing could have lasted considerably longer had law enforcement officials not moved in when they did.

While the authorities issued their private warnings to the possible targets on Monday, postal officials intercepted the 15th suspicious package possibly linked to Mr. Sayoc — this one addressed to the Atlanta headquarters of CNN — and Mr. Sayoc, shackled and dressed in a tan jumpsuit, made an initial court appearance in Miami.

Mr. Sayoc has been charged with crimes that could lead to nearly 50 years in prison and is accused of mailing explosive devices to some of President Trump’s most well-known opponents, including former President Barack Obama and former Secretary of State Hillary Clinton. CNN, which Mr. Trump has routinely condemned, was targeted last week and again on Monday, when postal officials in Atlanta recovered a package intended for the network’s headquarters.