>> adamant that is the scream of his son george zimmerman, rob zimmerman says in this case the law works. >> he continued to beat george. and at some point, george rolled his pistol. and did what he did. >> but trayvon martin's parents believe just as adamantly the screams of help were from their son, not george zimmerman. as for the amount of time that took place between when trayvon martin was shot and when you see the videotape of george zimmerman arriving, the special prosecutor will not clarify exactly how many hours had passed, because it's an ongoing investigation. so truly, it could be...