PLAINFIELD, Ind. -- A 26-year-old from California was charged in connection with several online threats made against high schools and a mall in Plainfield, Indiana, the U.S. Attorney's Office of Southern Indiana announced Monday.

Buster Hernandez, 26, of Bakersfield, was charged with threats to use an explosive device, threats to injure and sexual exploitation of a child.

The person made threats for weeks against Plainfield High School, Danville High School and The Shops at Perry Crossing in Plainfield, formerly called Metropolis.

In Feb. 2016, the person made one last post, saying the threats were fake. That person claims he hacked the iCloud account of a Plainfield student that he never met or had contact with. The person also taunted the police, saying the case will never be solved, and that they live an ocean away.

Investigators believe Hernandez is that person. He said he wanted to be the worst cyber terrorist who ever lived, according to transcripts of his messages to the victims.

"Terrorizing young victims through the use of social media and hiding behind the anonymity of the Internet will not be tolerated by this office," U.S. Attorney Josh Minkler said in a press release. "Those who think they can outwit law enforcement and are above being caught should think again. Mr. Hernandez's reign of terror is over."

Using different social media accounts, Hernandez would send the victims messages, according to the criminal complaint, with things like, "Hi _______, I have to ask you something. Kinda important. How many guys have you sent dirty pics to cause I have some of you?"

U.S. Attorneys believe Hernandez used Facebook to communicate with one female minor victim for 16 months, extorting her to send sexually explicit images to him, under the name "Brian Kil" in late 2015 and early 2016.

When she refused to provide more photos, he made more threats, saying, "I am coming for you. I will slaughter your entire class and save you for last. ... I will add a dozen dead police to my tally. ... Try me pigs, I will finish you off as well."

Minkler said Hernandez used a Tor network to mask his IP address, making finding him the "modern equivalent of looking for a needle in a haystack."

"The work to find him has been astronomical," Minkler said.

MORE | What took so long to arrest 'Brian Kil'?

Hernandez is also accused of exploiting and threatening at least two other minor victims, another from Indiana and a third from Michigan. Hernandez asked the Indiana victim to attend a community forum about the threats and record statements about the investigation, then report back to him.

"I need to you go and tell me what they say," he wrote to her. "Its (sic) Tuesday night at 7:30. I need to know what the feds have to say. ... I can't go. I fit the profile for the suspect. They will be looking for me. No one's gonna notice a black girl with an afro."

The 20-month investigation also included FBI investigators using a NIT, which is a small piece of code embedded in a photo or video. The suspect opened the photo or video, which allowed the FBI to find his true IP address, according to a criminal complaint document. The FBI set up surveillance outside his house before making an arrest.

"Buster Hernandez never stepped foot in Indiana," Minkler said.

Hernandez faces a mandatory minimum sentence of 15 years’ imprisonment, and a maximum of 30 years’ imprisonment if convicted on all counts.

Hernandez is accused of "sextorting" victims in at least 10 federal districts.

If you believe you have been a victim of sextortion by Buster Hernandez, contact the Indianapolis FBI Office at tips.fbi.gov or call 317-595-4000, Option 2.

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