proven under the law. >> jerry leoni is a former massachusetts district attorney and federal prosecutor. >> juries like motive. juries want to know why someone did something. especially when they've done something that's alleged to have been as heinous as this one. >> the defendant was the one -- >> a motive, no matter how trivial, would make the state's case stronger. prosecutors have already bolstered the case by upgrading the charges against the two men who were with hernandez the night odin lloyd was killed. ernest wallace, and another man, carlos ortiz. >> how do you plead? >> not guilty. >> this will be what's called a joint venture murder prosecution, where anyone who actively participates in the murder can be held guilty for the murder. >> that would mean hernandez could be convicted of murder, even if prosecutors can't prove