>> eddie canales: the heat and being unprepared. >> pelley: eddie canales works in the same county asckers' ranch. >> he crossed over through piedras negras? >> pelley: in 2013, canales founded the south texas human rights center, whiel rescue endangered immigrants and helps identify the dead. we came across the bodies of two men who apparently froze to death during a cold snap the other day. >> canales: they were young men. they were 18- and 19-year-olds. one was from mexico and one was from el salvador. >> pelley: how often are bodies found around here? >> canales: last year, 61 bodies were recovered. >> pelley: that's the ones you know about. >> canales: that's the ones we know about. the sheriff here will tell you that for every one recovered, there's five still out there. >> pelley: of these survivors, some are led by smugglers to safe houses, like these on the u.s. side, which were filmed by the border patrol. in days or weeks, their numbers grow, until there is a truckload. the migrants aren't told about the 18-wheelers until it's too late, and then they are forced to board. we