dr. latimer in dc. mom and parker walk in the building. >> she goes by beth. >> hi there. r. >> hi parker. okay, so the first thing i want you to do is look right at my nose, okay? >> reporter: dr. latimer spends over two hours evaluating parker medically. >> now turn your head over towards the window. >> reporter: learning his developmental history >> this was his cursive, and you can see it almost looks like. >> perfect. >> and then instead of cursive he started printing, and then his printing started to look more like, even before kindergarten. >> reporter: but most compelling, visual evidence dr. latimer gets to see is this. the dramatic, at times disturbing, home video the barnes's took to document their son's ordeal. >> come on. you can do it, son. >> is that the seizure? that's so scary. >> his eyeball's twitching. >> what made i start recording? >> because i couldn't believe it was happening, because i wouldn't have believed it myself if i told myself. >> this is so bizarre. it's like a short circuit in his brain. >> reporter: behavior ranging from unresponsive. >>