"It was a gift-wrapped package of poo, something a frat boy may do to another frat boy", he said.
A bomb squad was called in but after discovering the manure, they ruled it was not a threat to anyone's safety.
Once police opened it and saw the horse poop, investigators deemed the package non-threatening, KTLA reported Saturday.More news: Red Raiders fall to South Florida in Birmingham Bowl, 38-34
An LAPD bomb squad X-rayed the package before opening it and found the horse manure inside, police told local media.
Afterward, at least three officers could be seen standing around the pile, shining flashlights on the manure and moving it around with their feet, presumably to check whether anything else might be hidden in it.
Mnuchin is protected by the Secret Service, who have now taken over this investigation from the LAPD. The Secret Service said Sunday that it was "aware of this matter" but referred all questions back to Los Angeles police.More news: London Zoo fire kills one animal, several still missing
Strong posted several photos to Facebook on Saturday between 4:30 and 4:45 p.m. PST depicting a letter to Mnuchin and a picture of a gift-wrapped box in front of a palatial house.
It is unclear whether Mnuchin was home during the incident.
Treasury Secretary Steven Mnuchin got an early Christmas present on Saturday when a mysterious package addressed to him was found near his Bel-Air home late Saturday night. The Treasury Department did not immediately respond to a request for comment Sunday afternoon.More news: CWC members task Rahul with devising comprehensive electoral strategy