At a press conference on Saturday, police said they took the threat very seriously, and immediately scrambled several officers and detectives, the FBI Safe Streets task force, terrorism liaison, and tactical teams to investigate.
"Obviously in today's world a message like that is very concerning," Police Chief Michael Olivieri Jr said.
After identifying three potential suspects, they eventually narrowed it down to Villasenor via his "digital footprint" and descended on his Sylmar home, where he lives with his parents.
They said that after interviewing him, Villasenor admitted it was a hoax.
"He was planning to go to the fair on Sunday with his parents, and he did not want to go," the chief explained.
"Although he is 22, he felt it was appropriate to send this threat. We believe it was with the intent that it would spark some chaos and commotion, it would be captured on the media, and that then he could use it as an excuse to his parents to not go to the fair."
"Kind of a crazy thing, but that's what we have learned," he added.
Villasenor was taken into custody and is being held on $20,000 bail. Police insist they will seek to recoup the considerable money invested in the investigation.
Mass shootings at festivals and events are becoming increasingly common in the US; in July a 19-year-old gunman killed three people and himself, and wounded 17 more at the Gilroy Garlic Festival, a four hour drive away.
Organizers of the LA County Fair announced last month a $200,000 investment in security following the recent spate of shootings.
Indeed Chief Olivieri confirmed that in his 30 years on the Force, he had not seen more robust security measures being employed there.
We learned 9/13 of a possible threat. Working w/ Pomona Police & FBI were able to confirm that the threat was false. It's illegal to make threats & the individual was arrested. Fairplex would like to express its deep appreciation for the speedy response by Pomona Police & FBI. https://t.co/gBjYbtbvaQ
The Fair organizers confirmed the threat in a tweet on Saturday: "We learned 9/13 of a possible threat. Working w/ Pomona Police & FBI were able to confirm that the threat was false. It's illegal to make threats & the individual was arrested. Fairplex would like to express its deep appreciation for the speedy response by Pomona Police & FBI."
CEO of the Fairplex, Miguel Santana, also assured the press conference that the County Fair was safe to visit.
"Come here, have a great time, we have your back, we're here to ensure your safety," he said.