crops, growing resentments at the farm. >> robert told paul that he was going to get my share of what my dad was going to leave me of the ranch. >> your intention was to fight him. >> oh, yeah. it settles things. >> the investigation continues as explosives experts try to determine what exactly happened to roberto. >> he came across a piece of metal. that piece of metal said to him that there was something more going on. >> the first clue unearthed when ""dateline"" continues. [♪]