TUCSON, Ariz. (AP) -- The body of Ildefonso Martinez arrived on a Friday night last April as John Doe, Case No. 12-01000. He wore black Nike shoes, a Perry Ellis belt, jeans with a 34-inch waist, a Casio watch.
For medical examiners at the Pima County morgue, his was an unusual case. Not in how he died -- making the same arduous journey that has claimed thousands of illegal immigrants -- but rather because he was identified so quickly.
The death of migrants crossing the border has long been a tragic consequence of illegal immigration and, many say, the increase in U.S. border enforcement. For some, the problem is a powerful motivator in pushing Congress to act this year on immigration reform. But critics say proposals offered so far call for more enforcement with few specifics on how to save lives.
"The language coming out is alarmingly more of the same," said Kat Rodriguez of Coalicion de Derechos Humanos in Tucson, who gathers information on missing migrants from family and friends to give to medical examiners trying to identify the dead.
Thousands more Border Patrol agents, hundreds of miles of fencing, and cameras, sensors and aircraft have made it more difficult to enter the U.S. illegally, prompting smugglers to guide migrants to remote deserts. People walk up to a week in debilitating heat, often with enough bottled water and canned tuna to last only days.
While illegal crossings have dropped dramatically in past years, hundreds of bodies are still found annually on the border. Border agents conduct more than 1,000 rescues each year, and humanitarian groups have placed water stations along the boundary in hope of helping.
In the last 15 years, at least 5,513 migrants have been found dead along the 1,954-mile border with Mexico, including 463 in fiscal year 2012, the Border Patrol reports.
The Tucson sector -- which since 2001 has accounted for more migrant deaths than any other Border Patrol sector -- located 177 bodies in the last fiscal year. Texas' Rio Grande Valley saw the greatest jump in bodies found: 150 last year compared to 66 in 2011.
In that state, migrants cross the Rio Grande, catch a ride north and then hike for days on vast ranches in Brooks County to avoid a highway checkpoint. The county has no medical examiner and does not test DNA of deceased migrants, who are buried in unnamed graves at a cemetery in the town of Falfurrias.
The situation is similar to what Pima County authorities faced when Arizona became the busiest corridor for illegal crossings more than a decade ago.
"We had no idea this storm was on the horizon," said Bruce Anderson, a forensic anthropologist in Tucson.
At the Pima County Forensic Science Center on The University of Arizona Medical Center campus, file cabinets hold dossiers on more than 700 unidentified corpses discovered since the late 1990s. Many bodies were too decomposed to identify. Others carried false identification or no identification.
Coolers for 262 corpses and refrigerated trucks on call with room for another 45 give the nation's 30th-largest city one of the country's largest morgues.
"Nobody has this problem. Nobody," said Dr. Gregory Hess, Pima County medical examiner. His office rules on more than 2,000 deaths a year by murder, suicide and other causes, but migrants pose the biggest challenge because they so often cannot be identified.
Since 2001, the office has examined the bodies of 2,067 border crossers, the vast majority of them Mexican men. Men like Ildefonso Martinez.
Martinez, 39, was born and raised in a farming village in the central Mexican state of San Luis Potosi. After paying a smuggler some $200 to get him across the border, he settled in the San Diego area in the early 1990s and worked whatever odd jobs he could find.
Then last March, he agreed to watch the cash register at a friend's convenience store. A sheriff's deputy who required a signature on a regulatory notice turned suspicious when Martinez produced a Mexican consular identification card. The deputy called the Border Patrol, and Martinez was deported.
Left behind in California were his wife, Juana Garcia, and five children and stepchildren. Desperate to return to them, Martinez tried crossing three times in the mountains east of San Diego but was caught.
Then he decided to try his luck in Arizona. "It will be one night and one day, and we'll be there," Martinez told another crosser, Isaac Jimenez, whom he convinced to come with him.