YOUNGSTOWN, Ohio (AP) — An Ohio man accused of making an online threat against federal agents and voicing support for mass shootings has been indicted by a federal grand jury.

Justin Olsen of Boardman was indicted on charges of threatening to assault federal law enforcement officers and making interstate threats, the Justice Department said Wednesday.

Federal prosecutors said Olsen, who was arrested nearly two week ago, had been under investigation since February, but they decided to act now because of recent mass shootings across the U.S.

Court documents say that Olsen, 18, in June wrote about the 1993 standoff at the Branch Davidians compound in Waco, Texas, and said that federal agents “slaughtered families” and “in conclusion, shoot every federal agent on sight.”

Prosecutors said he also made statements before that on his iFunny page supporting mass shootings and attacks on Planned Parenthood.

Those same court filings said Olsen told FBI agents when he was arrested that the comments were only a joke.

His defense attorney said Wednesday that Olsen has no prior record and never faced any discipline in high school.

Authorities said they seized 15 rifles, 10 semi-automatic pistols and roughly 10,000 rounds of ammunition when they arrested Olsen at his father’s house.

Attorney Gerald Ingram said all of the guns belonged to Olsen’s father and that they were locked away in a storage area equipped with surveillance.

At a detention hearing last week, Eric Olsen testified that he had the guns and ammunition because he was a competitive shooter.

Olsen’s mother said her son had lived with her until about two weeks before his arrest when he moved out because he had become rude toward her lately.

She said she thought he might have anxiety about starting college, but also said she was worried that he was developing extreme antisocial views.