Photo Credit: Maria Martinez

The desert Zamboni, ready to resurface the road.

Pulling the drag is the first step when agents "cut for sign" along the drag road, the dirt path that runs a few yards north of our Border Patrol with Mexico. The drag road is meant to be a trap of sorts: only a ghost could get across it without leaving prints. "Sign" is the collective term for the evidence of which Ab Taylor spoke, the stuff agents look for and find-after they've dragged the dirt. It's footprints, animal prints, tire or bicycle tracks-any nick in the polished surface created by the drag that might lead the pursuer to the pursued. The term "cutting" refers to the practice of concentrating on the marks within discrete, manageable slices or segments of terrain. Trackers cut for sign to find illegal migrants, stranded hikers, lost children, errant livestock, even terrorists.

As the agent pulled the drag in November, one of the vehicle's wheels fell into a sinkhole so deep he couldn't drive out of it. So he radioed to another agent for a tow. The second vehicle managed to pull him out, but not for long. Both vehicles got stuck in a second hole about 20 feet away.

Man-made or geology?
Geologically formed sinkholes are found mostly east of Oklahoma and considerably north of the U.S.-Mexico border. Sign, however, is virtually always above ground. On top of that, the Border Patrol had stumbled upon an underground narco-tunnel in mid-September not 200 yards from where the second SUV got stuck. So this newest sinkhole looked more like sign than geology, but they couldn't be certain without an investigation.

Authorities on both sides of the border participated in the investigation, which confirmed the existence of a second tunnel. It was about 15 feet below ground, with a sophisticated lighting and ventilation system, and was cut in a zigzag pattern nearly identical to the tunnel found in September. It was also flooded, because whoever dug it had hit a water main.

The inquiry into the first tunnel led Mexican authorities to four men thought to have ties to the Arellano Felix drug cartel, whom they arrested. No arrests have been made yet in connection with the second tunnel, but the investigation continues.

Tracking and cutting for sign are as old as mankind, undeniably the earliest forms of detective work and forensic science. Where collecting evidence and solving crimes are concerned, these methods still hold their own against today's ultramodern computers and DNA analysis. Anyone who doubts that has only to watch an episode or two of TV's popular CSI series. Sometimes, as Ab Taylor was saying, you go out and look for the evidence. And sometimes, as in November's tunnel discovery, you just drop into it- the evidence comes to you.