jurors the prosecution had to prove its case against george zimmerman. and pointed out the prosecutor s own words lacked conviction. how many could have beens from the state in this case? how many what ifs? reporter: then mark o hara said he would do what he was not obligated to do, prove his client innocent. what followed was a three-hour summation soft spoken matter of fact style. if i walked in today and just as an example, walked in, like this. just walked into the courtroom as a lawyer, you would have an impression, what is he doing with his sunglasses and who does he think he is? you might have an impression of george zimmerman. you might have an impression of him because he s sitting at the defense table, and that may be as we talked about, he s not just the accused, but maybe he is a defendant or he has something to defend. reporter: he has the jury not to judge zimmerman by their first impression but to use common sense. if it hasn t been proven, as the instruction t