Paris Hilton has increased her security after a stalker pretending to be her fiance arrived at her father's office armed with a knife. The SIMPLE LIFE actress decided her personal safety had to take precedence after the deluded man, who police arrested, showed up at her dad RICK HILTON's place of business. She says, "I've had a lot of stalker incidents, and I usually can handle them. "But the scariest one was when a guy turned up at my dad's office and said he was my fiance. He forced his way inside and the cops discovered he had a knife on him. That was freaky. "Now I have a lot of security all the time so I feel safe. I guess that's one of the things you have to learn to live with, but it's still scary."