By ANITA SNOW, Associated Press TUCSON, Arizona (AP) — Alvaro Enciso plants three or four crosses each week in Arizona's desert borderlands, amid the yellow-blossomed prickly pear and whip-like ocotillo, in honor of migrants who died on the northbound trek. Each colorful wooden memorial denotes where a set of bones or a decomposing body was found. Over eight years, the artist has marked more than 1,000