They were poor men, barefoot farm labourers with pinched cheeks and calloused hands. But when they spoke, their bloodshot eyes flashed with cold steel. Four days earlier Muhammad Aslam, 35, and Maqbool Ahmed, 40, had killed their younger sister and her lover. It was a crude, gruesome death: the pair were battered with a brick and strangled with an old rope. But the killers expressed not an ounce of remorse.

"We feel no shame. They had been warned," said Aslam, a slightly built father of eight. "We did it for honour," said Ahmed defiantly. "In our society a man without honour is nothing."

A man's pride exacts a high price in hidebound rural Pakistan. Almost every day a woman is beaten, clubbed or shot to death for what is euphemistically termed "adultery" - sex outside marriage. In most cases the killer is a father, brother or uncle.

"There's an increased brutalisation of society," said Kamila Hyat of the Human Rights Commission of Pakistan, which recorded about 300 so-called honour killings in 2006 - about the same number as the previous year.

Occasionally one case is so shocking it dominates the news, even if for the wrong reason. Initial reports about the Donga Bonga killings suggested the lovers had been tied to a tree and stoned to death. The story was carried across the world. The image resonated powerfully with perceptions of Pakistan being gripped by Islamic fundamentalists.

The reports were wrong. There was no Taliban-style execution in Donga Bonga and Islam had little to do with it. But the truth - a tale of roguish men, powerless women and the shortcomings of a frail state - is no less compelling.

By all accounts, Ghulam Nabi Shah was a villain of renown. A burly man with a carefully combed moustache, he was the scion of a widely respected family in Chak Khatan, their home village. His father, Hafiz Ahmed Shah, was a Sufi mystic who was honoured with a tinsel-draped shrine. But Shah junior was more sinner than saint.

Several neighbours and the local police chief described Shah as a domineering character with a taste for banditry and bedding women. "He was a terrorist and a bully," said Zafar Bukhari, the district police officer. "He would beat the people and steal from them. We picked him up several times."

Smuggling

Shah's family was known to be involved in smuggling across the closed Indian border five miles away. India pays poor Pakistanis to sell sensitive information in return for cheap wine, police officers claimed. He was also adept at slipping from the law.

His record was expunged some years ago after the local police station caught fire. Detectives said he was suspected of killing a rival five years ago but the case collapsed due to lack of witnesses. "The villagers were even more sick of the other man, so nobody would come forward," said Mr Bukhari.

His downfall was his affair with Elahi Sain. The 35-year-old woman had left her husband a year earlier after a 10-year union that failed to produce any children. Shah started secretly courting Sain, sneaking into her bedroom in the compound she shared with her brothers.

But word of the scandalous liaison escaped. Ahmed and Aslam warned the couple to stop. "It was a disgrace. We went to Shah just after Eid [a religious holiday in early January]. We pleaded with him to stop. But he said we were talking rubbish," said Ahmed.

The final straw came a week ago, when a voice drifted from Sain's room just before midnight. Enraged, the brothers barged through the door.

Inside they found Shah hiding under a bed. Aslam wrestled him to the ground - "I bit his nose," he recalled - while Ahmed beat his head with a brick. Screaming curses, Shah reached for a pistol lying on a locker. But he couldn't make it. Shah passed out as blood oozed from his cracked skull. To finish the job, the brothers bound a rope around his neck and pulled.

Then they stormed into the next room, where Sain was cowering. Screaming, they dragged her out by the hair and murdered her beside Shah's body in exactly the same way. Then they locked the door, called a neighbour and waited for the police.

"It was a good job," said Aslam.

The murder has split opinions in Chak Khatan, a dirt-track Punjabi village surrounded by swaying mustard plants and freshly sprouting wheat. On Friday about 100 mourners crowded on to rope-covered benches around Ghulam Nabi Shah's mud-brick house. His 12-year-old son sat glumly in the middle. "This was a political murder. The woman was just an excuse," thundered Akhtar Hussain, an uncle.

An equally large crowd gathered near the murder scene, where an open door led to a blood-smeared bedroom. These men quietly approved of the killing. "It was the correct thing to do," said Sain's estranged husband. "She left me one year ago. She was not a good woman."

Gallows

Meanwhile, at nearby Donga Bonga jail, a burly warden watched over the two brothers, who claimed to have no fear of the gallows. Pakistan has one of the world's highest rates of capital punishment, with 7,400 prisoners on death row. Fifty-four were hanged in the first six months of last year.

"If we die, Allah will look after our children," said Ahmed flatly.

Rape and "honour killings" are an embarrassment to President Pervez Musharraf, who lightened the laws on "adultery" in November but under pressure from the religious right refused to abolish them entirely. An incident last week in which a woman was gang-raped and paraded half-naked through her village brought fresh revulsion.

"Every rape is a blot on the nation's tormented conscience," said the respected Dawn newspaper.

But although "honour killings" are often linked to Islam, they are more often a product of a poor, uneducated and deeply feudalistic rural society. Mr Bukhari, the police chief, said only schooling and greater prosperity - areas where Musharraf's military-led government has failed to make much progress - would end the phenomenon.

Human rights groups say better policing would also help. This week a police officer was shot in the shoulder during attempts to mediate in a land dispute between three brothers. To apprehend the culprits the police took their wives and daughters into custody - in effect making them hostages.

"All unofficially, of course," said one detective, who added that rough places required tough law. "That's always been the way of the Punjab police."