Socialite and baby-oil heiress Casey Johnson, who died last week in LA at the age of 30, was buried during a private funeral in New Brunswick, New Jersey yesterday morning. E! Online reports that those in attendance included Nicky Hilton, and her family — including father/Jets owner Woody Johnson, and her adopted daughter Ava. Her fiance, Tila Tequila, was reportedly not invited. TMZ reports that it's "increasingly looking like Johnson's frail medical condition — which included diabetes — may have caused her death."