sara dallap is in sanford, florida. >> reporter: good afternoon, thomas. what we can expect tomorrow is more key witnesses, perhaps the medical examiner and we are hearing trayvon martin's mother will testify in what should be some of the most emotional moments of the trial. the judge indicated yesterday that the prosecution would wrap up then, but some of those key technical witnesses easily fill the day. first we heard from the state firearms expert who testified about the contact shot that killed 17-year-old trayvon martin, contact mooens meaning the gun was actually touching the sweatshirt, his sweatshirt, when it was fired. we also heard from a police crime lab analyst who stated that he found neither trayvon martin's dna under george zimmerman's fingernails, nor trayvon martin's dna on the pistol grip of zimmerman's gun. the defense raising questions about its external factors like storage or temperature could have affected those dna