MEXICO CITY: A Frenchwoman who had spent seven years in prison in Mexico on kidnapping charges was flying back to Paris on Thursday after Mexico's Supreme Court ordered her freed because of flaws in her trial, bringing a close to a case that had strained relations between the countries.

Florence Cassez's arrest, trial and 60-year prison sentence made her a cause celebre in France, where two consecutive presidents called for her release. Anti-crime activists in Mexico vigorously opposed the Wednesday decision to free her.

Cassez's flight left Mexico City's international airport at 9:25 p.m. local time (03:25 GMT) and was expected to arrive in Paris about 10 hours later.

Relatives of kidnap victims angrily shouted "Killer!" as a police convoy with sirens flashing escorted a sports utility vehicle out of the Mexico City prison where Cassez had been held.

The family and supporters of the 38-year-old Cassez, who was arrested in 2005 and convicted of helping her Mexican then-boyfriend run a kidnapping gang, celebrated the decision, saying she was innocent.

"I'm crazy with happiness, I can't say anything else," her mother, Charlotte Cassez, said in France. "I'm still struggling to believe it."

Earlier on Wednesday, a Mexican Supreme Court panel voted 3-2 to release Cassez because of procedural and rights violations during her arrest, including police staging a recreation of her capture for the media. The justices pointedly did not rule on her guilt or innocence, but said the violations of due process, the right to consular assistance and evidentiary rules were so grievous that they invalidated the original guilty verdict against her.

One justice originally proposed on Wednesday asking an appeals court to review her trial, omitting the tainted evidence; however, most justices on the panel indicated they would oppose that, and they then voted to simply release her.

"If she had been turned over to court custody promptly, if she had been allowed prompt consular assistance, this (raid) staging couldn't have taken place, and the whole affair would have been totally different," Justice Arturo Zaldivar said during discussion of the ruling.

Because the case was mishandled, the truth remains unknown, said the president of Mexico City's Human Rights Commission, Luis Gonzalez Placencia.

"In this country we can no longer ignore police obtaining evidence by tampering with it, by using torture, by staging raids," Gonzalez said. "We will never know whether Florence is guilty or innocent, but we know for certain there are specific people who violated due process."

Wednesday's ruling put another spotlight on Mexico's historically corrupt justice system and drew reactions from both countries' presidents.

"I want to recognize the Mexican justice system because it put the law first," French President Francois Hollande said on television. "That was the trust we put in it. And today we can say that between France and Mexico, we have the best relations that it is possible to have."

Mexican President Enrique Pena Nieto said in a statement that he will "absolutely" respect the court's decision.

Agustin Acosta, an attorney for Cassez, called the ruling "a resounding message in favor of justice and respect for human rights." Police torture and fabrication of evidence have long been tolerated in Mexico.

Mexican police acknowledged they staged a raid on a ranch outside Mexico City to depict the hostages' rescue and Cassez's detention. After Cassez was detained and held incognito for a day, Mexican police hauled her back to the ranch and forced her to participate in the raid staged for television cameras, a type of display for the news media not unusual in Mexico.

The Frenchwoman said she had lived at the ranch, but did not know kidnapping victims were held there.

Cassez ultimately spent seven years in prison and became the center of a vigorous debate between Mexicans who say she was abused by the criminal justice system and those who say setting her free would only reinforce a sense that crimes such as kidnapping go unpunished.

The wife of one kidnap victim showed up on Wednesday as reporters gathered outside the Mexico City prison where Cassez had been held. Michelle Valadez said her husband, Ignacio, was kidnapped and held for three months by Cassez's boyfriend's gang in 2005.

"We paid the ransom, but they killed him anyway," she sobbed. "It's not fair what they've done to us, it's not fair they're freeing her."

Mexico has one of the world's highest kidnapping rates, and there has been increasing public pressure to halt what is seen as widespread impunity for criminals.

At least one victim identified Cassez as one of the kidnappers, though only by hearing her voice, not by seeing her.

It was not immediately clear how the ruling might affect the case against Cassez's ex-boyfriend Israel Vallarta, who is charged with allegedly leading the gang and is being tried separately.

But the ruling provoked a backlash from Mexican anti-crime activists, including Isabel Miranda de Wallace, who led a successful decade-long fight to bring her son's kidnappers to justice even though his body was never found.

"Today, they opened the door to impunity, today a lot of people are going to go free," Miranda de Wallace told news media. "We already live without public safety, now it's going to be worse."

Ezequiel Elizalde, a kidnap victim who testified against Cassez, told local media that the ruling discredited the Mexican justice system. "Get a weapon, arm yourself, and don't pay any attention to the government," he said.

Cassez was originally sentenced in 2008 to 96 years in prison for four kidnappings. The sentence was reduced to 70 years a year later when she was acquitted of one charge.

The case caused diplomatic tensions between France and Mexico. In 2011, Mexico said it would not participate in France's yearlong festival celebrating Mexican culture, after then-French President Nicolas Sarkozy said the festival should be used to draw attention to the Cassez case.

The trial underscored delays and irregularities that have long plagued Mexico's legal system.

Mexico in 2008 implemented a judicial reform that called for open trials and reinforced the principle of innocence until proven guilty. The old system, still in place in much of the country, was blamed for fostering corruption and confessions extracted by torture.