Laci was already "missing". How would Kim McGregor and the Hawaiians know where to find Laci to make her go missing again?
Oh, NOOO, Vel, you don't understand, see, Kim became infatuated by the alluring Scott BEFORE she actually had the privilege of meeting him! So, see, she had her ex-boyfriend's Hawaiian roommates kill Laci and hide the body, knowing that a search center would be set up, and that she could hang out there to bask in Scott's presence!
See, we really need to e-mail Mr. Geragos so he can explain these things to us.