On a hot desert morning last week, a group of 20 tourists gathered in the visitor center in Arizona's Organ Pipe Cactus National Monument to attend a mandatory safety briefing before taking a guarded van tour to Quitobaquito springs. The springs is part of the 69 percent of the remote border park west of Tucson that has been closed to the public since Kris Eggle, a 28-year-old law enforcement park ranger, was shot and killed while pursuing drug runners armed with AK-47s in 2002.