>> if anyone could do that, it was the defendant. ultimately, he had the potential to make that phone call. >> reporter: in testimony that was, frankly, mind numbing. >> that leverage is something called either tappy or j tappy. >> reporter: an expert from cisco, brad's former company, explained about ten different ways someone as accomplished as brad could have remotely made that call. >> the main ways to do it are using a computer where you can program something into your computer and delay it so that a phone call can be made from your computer from the computer's modem. >> reporter: to do that, brad needed a certain router. one prosecutor said conveniently disappeared from the cooper home. >> we know he had this router. >> reporter: in fact, said the prosecution, this cisco chat log proves brad borrowed that router, the 3825 it's called, took it home, months before the murder. >> you know that defendant had one of those two 3825 routers? >> that's correct.