The suspect, 25-year-old Dominic Luis Magdaleno of La Habra, has been booked on several felony charges including stalking, witness intimidation and criminal threats.
Investigators in Orange County started investigating his online activities after a 19-year-old woman came forward and accused him of harassing her on Instagram.
During a six-month investigation authorities collected evidence showing Magdaleno using popular social media platforms to stalk, harass and threaten multiple female victims.
In some cases, he allegedly threatened to sexually assault, rape and kill those victims.
Magdaleno pleaded not guilty at his arraignment and was ordered held on $500,000 bail.