Since then, his mother, Araceli Rodriguez, has taken it into her own hands to investigate her son's disappearance and has publicized the case inside and outside Mexico. She's found some clues about what happened but still doesn't have any certainty about her son's whereabouts.
As Mexican troops and police cracked down on drug cartels, who also battled among themselves, Leon was just one of thousands of people who went missing amid a wave of violence that stunned the nation. A new report by a civic participation group has put a number for the first time on the human toll: 20,851 people disappeared over the past six years, although not every case on the list has been proven related to the drug war.
With at least another 70,000 deaths tied to drug violence, the numbers point to a brutal episode that ranks among Latin America's deadliest in decades. In Chile, nearly 3,100 people were killed, among them 1,200 considered disappeared, for political reasons during Augusto Pinochet's 1973-1990 dictatorship, and at least 50,000 people disappeared during 40 years of internal conflict in Colombia.
The new database is shedding needed light on Mexico's unfolding tragedy. It's also sparking angry questions about why it doesn't include all of the disappeared.
Neither Rodriguez's son nor his six colleagues who went missing on Nov. 16, 2009, are in the database, which was allegedly leaked by the Attorney General's Office to a foreign journalist. The group Propuesta Civica, or Civic Proposal, released the data on Thursday.
Rodriguez's mother said she's been in touch with authorities investigating the case and has spoken about it in several public forums about the missing.
"I don't think any government entity has a complete database," she said.
A spokesman for federal prosecutors, who would not allow his name to be used under the agency's rules, said the Attorney General's Office had no knowledge of the document.
As compiled by Civic Proposal, the report reveals the sheer scope of human loss, with the missing including police officers, bricklayers, housewives, lawyers, students, businessmen and more than 1,200 children under age 11. The disappeared are listed one by one with such details as name, age, gender and the date and place where they disappeared.
Some media in Mexico have reported that the number of missing could be even greater, at more than 25,000, with their estimates reportedly based on official reports, although media accounts didn't make the reports public.
"We're worried because several of the people gone missing in the state of Coahuila, and that we have reported to authorities, don't appear on the database," said Blanca Martinez of the Fray Juan de Larios human rights center in that northern border state. She's also an adviser to the group Forces United for Our Disappeared in Coahuila, made up of relatives searching for loved ones.
Martinez said that between 2007 and 2012 the group registered 290 cases of missing people. The database released Thursday lists 272 cases in the state since 2006.
"We have no doubt that the authorities have done absolutely nothing" to solve them, she said.
Public attention to Mexico's disappeared has grown especially since 2011 when former President Felipe Calderon publicly met with members of the Movement for Peace with Justice and Dignity, a human rights group led by poet Javier Sicilia. His son was allegedly killed by drug traffickers that same year.
Sicilia's movement demanded that the thousands of killed and missing should be treated as victims of the drug war, even if they were criminal suspects. Calderon's government responded that it would create a missing persons database, but authorities have not made it public so far. Calderon also ordered the creation of a special prosecutor in charge of assisting crime victims and supporting the search for the missing.
"There is nothing worse for me than having a missing relative. Not knowing where the person may be is very serious and so ... in every case that comes to us, we try to find a solution, to find the person," said Sara Herrerias, the head of Provictima, the office established by Calderon to help crime victims.
Herrerias, however, was cautious talking about the number of missing and said she could only discuss the cases that her office has dealt with.
In 14 months, she said, Provictima has handled the cases of 1,523 missing people, most of them allegedly taken by members of organized crime but with some cases also reportedly involving government authorities. Of the total number, 150 people have been located, 40 of them found dead.
Herrerias declined to talk about the possible magnitude of disappearances. "I don't like to talk when I don't have hard data," she said.
Estimates of the missing vary. The National Human Rights Commission, which operates independently from the government, has said that some 24,000 people were reported missing between 2000 and mid-2012, in addition to some 16,000 bodies that have been found but remain unidentified.
The government of President Enrique Pena, who took office Dec. 1, estimates the number of unidentified bodies at about 9,000 during Calderon's previous six-year administration.
Civic Proposal director Pilar Talavera said that although her group saw inconsistencies in the database, they decided to disclose it not only to help the public understand the scale of the violence, but also to pressure authorities to disclose official information on disappearances.
While the numbers help, what the relatives of the missing need most, of course, is to just learn what happened to their loved ones.
Since the disappearance of Rodriguez's then-23-year-old son, a dozen alleged members of the La Familia drug cartel have been arrested as suspects in his case. Rodriguez said she has interviewed four of them, who have told her that her son and the other six officers were killed and their bodies "disintegrated."
She said that so far no one has given her any clues about where her son's remains are.
"If it's true what the criminals say ... even with that, my heart asks to find Luis Angel," Rodriguez said. "For me Luis Angel is still missing."