The suspect reportedly threatened both Shapiro and his family. Sources told the outlet the threats were "extremely serious."
Shapiro, who currently serves as editor-in-chief of The Daily Wire and hosted an election show on Fox News last year, filed a report with the Los Angeles Police Department related to the threats, according to TMZ.
The agency, along with the FBI, reportedly created a joint task force to search for the suspect.
The 35-year-old author made light of the situation online, tweeting about the photo TMZ chose to publish of him. He appeared to be donning a Minnesota Twins hat, which he called "slightly humiliating, however. #whitesox forever!"
He followed up: "(For the record, I own all of the MLB hats, and I switch them out when I travel.)"