But Montano is alive and well in the city of Tijuana, hundreds of miles away near the U.S. border, the victim of different enemies: incompetence and indifference in a land where authorities have failed to identify thousands of people killed in grisly gangland violence.

"Legally, I'm dead," Montano said, standing in the same Tijuana street where his death certificate says he was gunned down with shots to the neck and chest. "They buried me to banda," he said, referring to a brass-based traditional music genre popular in Mexico.

Who the bullet-riddled corpse buried in his coffin last year in the western beach resort of Mazatlan belongs to is anyone's guess.

In a gross comedy of errors, Montano is now in legal limbo as he tries to reinstate his identity with the public records office. His 'death' illustrates the administrative chaos that families of drug war victims often face in Mexico.

For many, the nightmare never ends.

"All I want is to find my daughter," said Luz del Carmen Flores, clutching a photo of Angelica, who disappeared in the violent border city of Ciudad Juarez in 2008. Aged 19, she left her home one day in search of work and never returned.

Flores has searched relentlessly for Angelica, looking in seedy bars, traveling to follow up leads and regularly standing in public squares with pictures in case someone recognizes her daughter.

Police called her in to review two bodies, neither of which was Angelica. Beyond that, Flores say they have done nothing to help her and others looking for missing relatives.

"They want me to look for her accepting that she is dead, but I look for her alive ... The only information they have is what we investigate using our own money and risking our own lives. Those who took them don't want us looking for them."

"For these past 6 years, I have felt like a zombie."

Authorities' failure to catch the killers in the vast majority of cases or even identify many of the dead is largely down to poor police work and a haphazard patchwork of forensic services across Mexico.

It also helps fuel impunity and further violence. More than 100,000 people have been killed since former President Felipe Calderon ordered a military offensive against drug gangs in late 2006, a move that led to waves of extreme violence.

Despite repeated requests by Reuters, the attorney general's office did not say how many victims are yet to be identified.

But partial figures from the National Human Rights Commission offer a glimpse: Between 2006 and 2011, more than half of the 40,000 people reported killed in armed confrontations were never identified.

Since 2006, only 336 of some 2,000 corpses exhumed from mass graves scattered across the country have been matched with a name, according to official data obtained by Reuters via freedom of information requests.

The figures often don't match those reported by state authorities. Durango state reported 300 corpses were found in mass graves in 2011, but data from the attorney general's office mentioned just 20 bodies.

CONFUSION

Even when remains are officially identified, terrible mistakes have been made.

Elvira Garcia has spent the past decade looking for the remains of her husband, who was kidnapped and murdered in Tijuana. His remains were then buried by authorities in a mass grave.

She knows her husband is dead because she saw a photograph of his corpse posted on the Web site of Tijuana's forensic service.

But then she found that someone else's file accompanied the picture, and that her husband had been misidentified as a kidnapper rather than a victim.

Desperate, she obtained a permit and paid a funeral agency 50,000 pesos ($3,820) to exhume his remains. But his body was not there and Garcia now believes it is in another mass grave.

"We have had to endure so many things, even humiliation," said Garcia, who works as a factory accountant. "After all this time, you wind up devastated as a family. All we want to know is where he is. Why have there been so many errors?"

Experts say Mexican institutions use flimsy forensic protocols. Latin America's No.2 economy also lacks a centralized database that would enable cross-checking of unidentified remains against lists of disappeared.

"The problem isn't the technology, that's available, but rather the way the data is gathered," said Christof Heyns, the United Nations special rapporteur on extrajudicial killings.

President Enrique Pena Nieto has staked his reputation on pushing through ambitious economic reforms, especially in energy and telecoms, and some researchers and victims believe his government does not view modernizing forensic procedures and identifying the disappeared as priorities.

Pena Nieto recently made good on a campaign pledge to launch a new Gendarmerie police force to fight drug violence. But it is a fraction of the planned size and its mandate is now to protect productive sectors of the economy hit by extortion, like mining and agriculture.

Little is being done to fix the shortcomings in identifying human remains that have led to dramatic mistakes, like sending corpses to the wrong families.

A report by the Inter-American Commission on Human Rights noted the case of a Honduran man who was killed in a 2010 massacre of 72 mainly Central American migrants on a ranch in the northern Mexican state of Tamaulipas.

Three months later, his mother received a sealed coffin filled only with a black briefcase, 17 plastic bags and a piece of meat mixed with dirt and worms.

Montano's family was never allowed to view the corpse believed to be his. No explanation was given, and instead they were asked to confirm his identity using only photos.

HELPLESSNESS

Other family members had their doubts but ultimately confirmed his identity because they did not want the remains to be buried in a mass grave in case it was him.

"I saw the photos and even though I hadn't seen him in 10 years, I knew it wasn't him," said Anselmo Mora, Montano's half brother.

"I asked if the body was missing a testicle, like Carlos. They told me it was." The family believes it was a lie, however.

Pena Nieto's government says it has purged a list dating from Calderon's administration, and that there are 22,322 missing persons in Mexico.

The actual list has not been made publicly available. Asked for a copy, Mexico's public records authority said it had no knowledge of it.

At a recent forensic operation on the outskirts of the northern border city of Mexicali, which Reuters attended, a small group of officials poked the desert surface with metal rods in search of bodies.

A trained dog sniffed at each hole but seemed disoriented by the stench of garbage, decomposing animals and raw sewage at the site. After hours working under a blazing sun, one officer found what appeared to be human finger bones. He picked them up with his bare hands and tucked them into a small plastic bag, in violation of guidelines.

The operation was triggered by a tip-off from a cartel member now in a witness protection program, but ultimately no bodies were found that day.

Mexico's violent cartels sometimes dissolve victims' corpses in acid, chop them into many pieces or mix them with animal parts, making identification extremely difficult.

Santiago Meza, a cartel butcher, admitted in 2009 that he dissolved 300 bodies in acid at a ranch just outside Tijuana. His drug gang alias was 'The Stew Maker'.

Such is the challenge authorities face that Ricardo Garcia, a top human rights official at the national state prosecutor's office, quit in May saying he felt unable to help victims' families.

The problem is particularly acute on Mexico's border with the United States, where some of the bloodiest chapters of drug violence have played out. Experts say thousands of people are believed to be have buried by their killers along the border.

Relatives of some of the missing refuse to give up, saving a place at the dinner table, celebrating their relatives' birthdays and even buying them Christmas gifts.

But most are resigned to the fact their kin are dead and they simply hold out hope of recovering their remains.

Garcia, the accountant, has all but lost hope of burying her husband.

"They don't even pick up the phone," Garcia said of Mexico's authorities. "The truth is I don't think the government is going to do anything for us." ($1 = 13.0863 Mexican peso) (Reporting by Lizbeth Diaz; Writing by David Alire Garcia; Editing by Simon Gardner and Kieran Murray)