Details on the FBI's years-long tracking and eventual arrest of an alleged sextortionist have been released thanks to the unsealing of documents related to the investigation. A 26-year-old California man operated under the alias Brian Kil to extort images of a sexual nature from children as young as 12, Engadget reported Wednesday. The man, whose real name is Buster Hernandez, has now been federally charged with threats to use an explosive device, threats to injure, an sexual exploitation of a child.

In 2015, the Brownsburg Police Department in Indiana reached out to federal authorities involving a "cyber-threat" incident involving a minor. The alleged sextortion tactics between this victim and the suspect continued for 16 months, during which a refusal to send more pictures was met with violent threats. "I am coming for you," Hernandez allegedly said in one message. "I will slaughter your entire class and save you for last." The nature of the suspect's threats—which are also alleged to have included mentions of explosive devices—ultimately forced a temporary school closure.

All told, Hernandez is accused of using similar sextortion tactics on multiple victims in at least 10 federal districts. 

Eventually, in June of this year, the FBI was granted permission from a judge to access a Dropbox account connected to an alleged Michigan victim. A non-pornographic video was then sent from the alleged victim's computer, upon receipt of which the FBI—thanks to some clever coding—would be alerted to the suspect's IP address by way of malware. The computer was tracked, ultimately leading to Hernandez's arrest.

"The FBI told us that this would be a long investigation and they were right," Plainfield Police Chief Darel Krieger said in a news release from the Department of Justice Monday. "However, with dogged determination they have apprehended a person who they believe is the person who posed as Brian Kil. We are grateful not only to the FBI but to all the agencies involved in this investigation (federal state and local) and the great partnership that was shown over the past 20 months."

If convicted on all charges, Hernandez is facing a minimum of 15 years and a maximum of 30 years behind bars.