Ronald James Wooden flexes the large blacksmith's hands with which he once forged everything from large chandeliers to intricate jewelry. He's says he is still regaining feeling in them three years after a four-hour beating with fists and rifle butts by municipal police in southern Mexico.

The officers tightened his handcuffs and then stood on them to inflict maximum damage to his hands, said Wooden, 46, who had set up a workshop in the hills outside the silver-mining city of Taxco along with his Mexican-born wife. Police detained him for allegedly disturbing the peace, but Wooden says the beating arose from a dispute with his neighbor, a former cop who claimed to belong to a local drug cartel.

"They beat me for close to four hours. Some would get tired and then others would come in. They were going to kill me and disappear me," said Wooden, who said he suffered nerve damage, broken ribs and injuries to his genitals.

He said what saved him was "divine intervention and the love that my family has for me." His wife, Carmen, waited outside the police station for hours until she was allowed to pay Wooden's 200-peso ($12 fine) and took him to a hospital after he was released.

Human rights groups say police torture remains all too common in Mexico, but Wooden's case from 2013 is unusual in two respects: He's an American citizen and he's won a court order for a criminal investigation into the beating.

A probe in 2014 by the governmental Human Rights Defense Commission in Guerrero state found that Taxco police illegally detained Wooden, contradicted themselves about how he sustained his injuries and essentially lied about their extent. It found that the American had been covered in bruises, scrapes and cuts.

The commission issued a directive that municipal authorities should punish those responsible and pay reparation.

After two years of no action, a federal judge on June 30 ordered Mexico's government to open a formal criminal investigation for torture and kidnapping in Wooden's case.

"This opens a new road, little explored and little used" to force authorities to investigate the thousands of torture complaints in Mexico, said Mario Santiago, a lawyer for the human rights group Idheas, which is representing Wooden. "We know there are hundreds or thousands of torture complaints all the time in the country. There is no investigation; these go unpunished."

Wooden, who had been living in Texas, was drawn to Taxco by its famed silver jewelry industry, which had been revived by American adventurer William Spratling in the 1930s. But in recent years, the colonial-era town south of Mexico City has been in the grip of drug cartels. In 2010, authorities discovered 55 rotting bodies that had been tossed into an abandoned mine shaft near Taxco.

Wooden said that as soon as he set up his shop, he began receiving threats from a neighbor who claimed to be a member of the Guerreros Unidos drug gang and demanded a 10,000-peso monthly protection payment.

When the neighbor got out a machete and threatened to send Wooden back to the United States in pieces, both men called the police, Wooden said. He said that when officers showed up, they went straight for Wooden, kicking and punching him to the ground. They arrested him for being drunk and disturbing the peace — allegations he denies.

Wooden is under no illusions about what could have happened to him: Taxco's police were so notorious that the federal government disarmed the whole force a year and a half after Wooden's arrest and handed policing over to federal officers.

The city's former police chief, Eruviel Salado Chavez, was arrested last month on charges of organized crime and kidnapping. He is accused of close ties with Guerreros Unidos, which is blamed for many of the 100 bodies found in mass graves around Taxco and the nearby city of Iguala. The federal government says 43 college students who disappeared in 2014 in Iguala were kidnapped by corrupt municipal police and turned over to Guerreros Unidos, which supposedly killed them.

"Part of what has protected me is that I'm a foreigner, and I have no fear," Wooden said. "What happened to me has happened to other people ... Whole families have disappeared in those situations."

He said that when he came to his senses in the jail cell after the beating, "I realized that there is dried blood on the floor, and it's not mine so much."

Mexico passed a law setting out punishment for police abuse in 1986 amid horror over the discovery of tortured bodies at an earthquake-damaged police headquarters. The law, on paper, was toughened in 1991, banning the use of testimony obtained under torture.

Still, scandals involving Mexican police, soldiers and marines keep mounting. And Wooden's case is an example of how hard it is to punish such abuses.

The artisan initially filed a criminal complaint after the beating. But he said he dropped the effort when a man at the magistrate's office pulled him aside, saying: "They're planning to disappear you from here if you continue to make noise and press charges.'"

Besides suffering physical damage, Wooden said some of his equipment was stolen. He and his wife left Taxco, fearing for their lives, and moved to other parts of Mexico. He said he's been unable to get new projects due to his injuries and a lack of money to buy materials.

Nobody has gone to jail for torturing Wooden. Two of the police officers got warnings and were required to take human rights classes, though Santiago said it's unclear if they did.

"There is no investigation, these go unpunished. What happened to him happened to a lot of people," said Santiago. "What we are looking for is structural changes, so these abuses don't continue to happen."