MEXICO CITY, Dec. 14 -- Her mother asked that mourners wear white, so the memorial service Saturday for Silvia Vargas Escalera seemed less grim than the circumstances surrounding one of Mexico's most notorious kidnappings.

The body of the wealthy and vivacious Mexico City teenager was found last weekend buried under a patio in a house south of the city. She had been missing for more than a year. Her remains were identified by dental records and DNA on Thursday.

The abduction and killing of the 18-year-old student, whose fresh young face had been ubiquitous in the news media here for months, have stoked outrage and revulsion in Mexico. The public is frustrated not only by waves of violent and often organized crime, but also by the government's inability to solve cases and put the guilty behind bars.

Many people, too, are afraid of the kidnapping crews, which no longer limit their targets to the super-rich, and travel in armored cars and with bodyguards. Kidnappers now snatch middle-class and even poor victims, demanding as little as $500 in ransom for their return.

The Vargas case is especially gruesome and revealing. Unlike so many kidnappings in Mexico, where victims' families often do not report the abductions and instead attempt to privately negotiate and pay ransoms, the Vargas case played out in public view.

Her father is Nelson Vargas, a former cabinet secretary and former top sports official. The family spoke at emotional news conferences, offered rewards and begged the kidnappers for her return. They put up huge billboards with her photograph. They also performed their own investigation, while accusing the police of bungling the case.

"This was not just a crime against a young woman and her family, but a crime against the public. It stokes this sense in Mexico that no one is really safe, that anyone can come and grab you off the street. And that the police are useless or worse," said Ricardo Ainslie, director of a documentary film, "¡Ya Basta!" on the rash of Mexican kidnappings and professor at the Institute of Latin American Studies at the University of Texas. "It makes people feel angry and then hopeless. It is like a collective trauma."

The Vargas family posted its invitation to the Saturday memorial service on the Internet. After her remains were identified Thursday, the family issued a statement that began: "We know that Silvia is with God. We ask everyone to pray for her and all those people who have suffered the same pain that we have felt since Sept. 10, 2007," when she disappeared on her way to classes. A week later, the kidnappers sent her family a bag of her belongings, a so-called proof of life that often begins ransom negotiations.

At the memorial service before an afternoon Mass, a line of mourners, many dressed in white, hugged the parents and siblings, who stood before a large portrait of the Virgin of Guadalupe, the patron saint of Mexico. In the back of the hall was a wall covered with snapshots of Silvia Vargas -- as a child at the zoo, as a girl playing at the beach, as a young woman, her arms draped around her father's neck. Mexican President Felipe Calderón was one of the first to arrive to pay his respects.

Last month, after Silvia had been missing for more than a year, her family held a dramatic news conference that drew back the curtain on how the Mexican police investigate kidnapping cases. Fighting back tears, Nelson Vargas said, "I have cried. I have begged. I am now demanding that Attorney General Eduardo Medina Mora and Public Safety Secretary Genaro García Luna resolve this case." Medina and Garcia are Mexico's top federal law enforcement officials.

"Find my daughter," Vargas said. "Find my Silvia."

Vargas revealed that early on, the family suspected that their former driver, Oscar Ortiz, may have been involved. Vargas said he told police his suspicions. Only later, Vargas said, did a tipster who had seen news coverage of the case tell him that Ortiz's brother was one of Mexico's top kidnapping suspects.

In fact, two of the chauffeur's brothers -- Manuel Ortiz and Raúl Ortiz -- belong to Los Rojos, a kidnapping gang, according to police. During the news conference, Vargas asked how the police could have missed that fact. "So I ask myself, where is the intelligence? They don't see the obvious. What can we expect from their investigations?" he said.

The attorney general's office confirmed to reporters that the Ortiz brothers were wanted on suspicion of kidnapping but said investigators did not know that Oscar Ortiz had worked for the family until Vargas informed them in October. The Vargas family, however, said they had told police about the chauffer shortly after the kidnapping.

On Friday, the Mexican newspaper Excelsior published a graphic to accompany its coverage of the Vargas case that listed other reported errors made by police, including a failure to identify the cellphone number used by the kidnappers the first time they contacted the family; not examining images from at least 40 video cameras along the route Vargas took to school; and not taking fingerprints from the bag the kidnappers sent as proof of life.

The Vargas family chauffer was apprehended in southern Mexico last month and is being investigated, but he has denied involvement, police said. His brother Raúl was sentenced to 16 years in prison for kidnapping in 1996 but escaped in 2000 by hiding in a clothes container that was being removed from the prison, the Associated Press reported. Raúl Ortiz was recently detained again in Mexico City but escaped from a hospital where he received treatment.

María Elena Morera, president of Mexicans United Against Crime, which has organized rallies to push the government for crime-fighting reforms, called the Vargas investigation "very bad." Morera referred to the government's latest figures showing that kidnappings were down 18 percent in the past three months and that more than 50 kidnapping gangs have been dismantled since new measures were taken. "But it is not enough," Morera said.

According to the office of the federal attorney general, kidnappings average 72 a month nationwide. However, an independent research group, Citizens' Institute for Crime Studies, estimates that 500 people are kidnapped each month nationwide but that most abductions are never reported because victims' families fear the kidnappers and corrupt police, who often work together.

This year, the 14-year-old son of sporting goods magnate Alejandro Martí was kidnapped and killed. His body was found rotting in the trunk of a car. Authorities suspect a federal police officer was involved in the abduction.

The level of frustration is so high that the governor of the state of Coahuila has proposed rewriting the constitution to allow for the death penalty in kidnapping cases. Executing kidnappers has broad public support. Even the Green Party of Mexico, which usually concerns itself with environmental issues, has endorsed the idea.

"What does the Silvia Vargas case show? It shows to the authorities that citizens are forced to do their own investigations," said Javier López Adame, a leader of the Greens. "It was her father who did the investigation, and thanks to him they found the body of his daughter. I mean, the authorities failed totally."

Calderón has proposed life sentences for kidnappers.