Yes, it is true. French people omit the "ne" all the time in informal contexts and this involves some phonetical changes:
Je ne sais pas --> Je sais pas --> j'sais pas (often pronounced as "chépa")
Je ne vois personne --> Je vois (j'vois) personne
However, you should be aware that the standard, correct form is "je ne sais pas" and be ready to use it in formal contexts.