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MIAMI (CBSMiami) – We are learning new details about the internet searches investigators say accused serial bomber Cesar Sayoc undertook as he targeted at least 15 prominent Democrats and critics of President Trump this month.

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In a letter sent by attorneys with the Department of Justice to the federal judge handling Sayoc’s case, prosecutors write:

“The evidence of the defendant’s terror campaign is still being collected but is already overwhelming. Because of the powerful proof that the defendant perpetrated these acts, he poses a substantial danger to the community. In light of the consequences at issue and the likelihood of conviction, the defendant is also a substantial flight risk. Therefore, pretrial detention is appropriate.”

The hearing on Sayoc’s bond will be held on Friday morning at 10 am in Miami.

The letter also shares some of the information gleaned from searches of Sayoc’s laptop, which was recovered from the sticker-covered van espousing hate and violence that he was living in as well as his cellphone.

The letter says a search of the laptop reveals that Sayoc likely began planning his crimes in July due to the creation date of a file called “Debbie W.docx.” The document also reveals that on September 18 Sayoc searched the web for “vice-president-joe-bidens-house- former/view” and that he also searched his victims and their families. Some of the searches listed are:

“george soros and family”

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“hilary clinton and family”

“james clapper wife and kids”

“eric holder wife and kids”

“john brennan wife and kids”

Federal prosecutors say Sayoc’s phone also contained photos of some of his victims along with photos that “purport to be the home of former President Obama, the home of former Vice President Biden, and a driver’s license belonging to former First Lady Michelle Obama that includes another address.”

The feds said that they linked Sayoc to the packages through a pair of fingerprints as well as DNA components found on 10 of bombs.

Despite his past criminal records, the letter says Sayoc “was repeatedly sentenced to terms of probation and he appears to have violated the terms of his probation at least twice since 2015.”

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As for why Sayoc needs to be jailed prior to his trial, prosecutors write, “previous lenient sentences were insufficient to deter the defendant, and he has never faced the type of sentencing consequences at issue in this case, which creates still greater incentives for him to flee.”