Horses**tgate continues.

On Sunday, the Los Angeles Police Department and U.S. Secret Service investigated a mysterious package left outside the Bel Air home of Treasury Secretary Steve Mnuchin. Authorities eventually discovered the box was filled with horse manure.

Now, a psychologist for the Los Angeles Department of Mental Health named Robby Strong tells AL.com he is the one behind the delivery.

Strong says the prank was activism in response to the Republican tax bill passed last week.

“The fact that [Republicans] can be so brazen and act with such impunity tells me that we have to be more brazen with our activism and maybe a bit more aggressive,” he told AL.com.

On Saturday, before the package arrived at Munchin’s house, Strong posted this series of photos to his Facebook page, saying he needed someone to help “document my Secret Santa project” in which he would “hand deliver boxes of horse shit to Steve Mnuchin.”

In the photos, he shows the box filled with horse manure and takes a selfie with it.

Soon after, Strong posted a photo of the card he allegedly included with the package. It’s signed “The American People,” which is consistent with what the LAPD told The Guardian about the letter that came with Mnuchin’s delivery.

Strong shared the news story on his Facebook page Sunday morning with the status: “Well, looky there. Who could’ve done such a thing?”

The package naturally caused some alarm, leading the LAPD to call in a bomb squad. But Strong, who was later visited by Secret Service agents, dismissed the seriousness of the situation.

“This is a glorified frat boy prank,” he told the New York Daily News. “How much can you punish someone for dropping box of doodie?”

Strong is not currently facing any charges.