he said the real killer was his friend, 19-year-old isaac brown. brown, who had no criminal record also confessed but said the killer was caballero, who was broke and desperate for money. brown said caballero had been planning to rob denise for months. >> there was just loose talk from caballero saying that man, i need to come up. i need to hit somebody. i need some money right now. and only person i could think of that has got some money right now is right there. and he would always point across the hallway. >> everybody and their brother was trying to make a deal with the devil. in other words, every bad guy in this case was wanting to confess and plead out but get the best deal they could. >> brown's prints were found on a soda bottle in denise's car. proof he was involved. despite brown and caballero's conflicting versions of what happened their stories were identical on one count. they had breakfast together just hours after dumping denise's body in the canal. >> they went to an i-hop restaurant. >> investigators tracked down the receipt for th

isaac dovere, we thank you both. >> thank you. >> ifill: and finally tonight, an extraordinary honor for an extraordinary deed. jeffrey brown our story. >> reporter: by november, 2010, u.s. marines were nine months into the first big push of president obama's afghan surge to re-take marjah, a taliban- held district of southern helmand province. lance corporal kyle carpenter was 21, part of "f" company, 2nd battalion, 9th marines. >> we were tasked with pushing south into an enemy stronghold territory and it was pretty simple. i mean, we were just tasked with taking over a new compound. >> reporter: but things didn't quite go that easily, right? the enemy was getting closer and closer? >> they were. we knew it was gonna be bad. we knew we were probably gonna take casualties. we didn't know how bad but when we got down there, very shortly after moving in, got our first grenade attack, it became even more real than what we had anticipated. >> reporter: more real. tell me, what does that mean? >> well, i mean, up until that point, for months and months, our worries were i.e.d.s, stepping on i.e.d.s, and pretty much from sun up