The federal investigation that led to last week's arrest of an Ohio teenager, who prosecutors said had more than 10,000 rounds of ammunition and over two dozen guns inside his home, started in Anchorage.

Justin Olsen, 18, faces a charge of threatening to assault a federal law enforcement officer.

FBI agents arrested Olsen on Aug. 7 at his father's home in Boardman, Ohio, just south of Youngstown. A federal affidavit says agents found 25 guns, including AR-15 style rifles and shotguns. They also discovered a large machete in the trunk of Olsen's car, ammunition, camouflage clothing and backpacks.

The affidavit says FBI agents in Anchorage started the investigation back in February when they focused on a user profile on the popular meme-sharing website and app iFunny.

The user, "ArmyofChrist," is said to have posted threats, discussed supporting mass shootings and talked about targeting Planned Parenthood.

"ArmyofChrist" also discussed the 1993 siege in Waco, Texas on June 2 with another user, according to the affidavit. That conversation included a threat "shoot every federal agent on sight."

The FBI issued a subpoena in late March to iFunny for information about "ArmyofChrist" and later received information about its associated email address. 

A second subpoena went to Google in July for information about the account. Google told the FBI the account belonged to Justin Olsen with an IP address associated with an internet service provider in Ohio.

The FBI in Anchorage turned the investigation over to the FBI in Youngstown in early August. Agents there found other posts from "ArmyofChrist" that said, "don't comply with gun laws, stock up on stuff they could ban. In fact, go out of your way to break these laws [...]"

In an interview after Olsen's arrest, he admitted to posting and making the violent comments on iFunny, but said they were "only a joke," according to the affidavit.

U.S. Attorney for the Northern District of Ohio Justin Herdman said while Olsen might have said the posts were a joke, law enforcement always takes threats seriously. He also credited the Anchorage FBI for breaking the case.

"This is great investigative work. FBI Anchorage really did a solid job in following up on this information, passing that information off as appropriate to our local field office here in Cleveland and Youngstown," he said. "Then ensuring the investigators here in Ohio had all the information we needed to identify the person who made the threat, and to make sure that local law enforcement was advised of that."

Olsen remains in the Mahoning County jail with a detention hearing set for Friday.

Copyright 2019 KTVA. All rights reserved.