test the defense claimed would have revealed if he actually fired that gun that night. >> if you've ever seen what that gun looks like, everything just comes out the side of that cylinder. so that stuff goes somewhere. and onto your skin is where you're looking for at it. >> yet they didn't look. >> they didn't look. >> but he's a cop, they're a cop. >> brett seacat doesn't have much faith in the kbi. >> but the star witness for the defense would be the last witness, brett seacat himself. coming up -- cold-blooded killer or grieving husband? >> i didn't think it was appropriate to be dragging my wife's name through the mud. >> did you love vashti? >> i loved vashti. >> did you kill vashti? >> no, i did not. >> brett's story from the stand, his life on the line.