Shortly after midnight on June 8, Officer Danjuma Ibrahim fired an automatic rifle into a carload of six young people at a police checkpoint in this capital city, according to public testimony. The driver, Ifeanyi Ozor, 25, died instantly. His fiancee, Augustina Arebun, 22, bloodied but alive, let out a wail of anguish.

Over the next few hours, officers involved later testified, police drove Arebun and the other passengers to a remote location and executed them all. They planted guns and knives in the bullet-riddled car, posed the bodies around it for official pictures and announced that six dangerous armed robbers had been "killed in combat" with police.

In the past, according to Nigerian and international human rights groups, such crimes never would have been investigated or exposed. Each year, the groups report, hundreds of people die unlawfully at the hands of police officers, with no official acknowledgment or action.

But this time, because of a brief, desperate cell-phone call made by one victim shortly before he was killed, the truth began to emerge and public pressure mounted, ultimately cracking what human rights activists said had long been an impenetrable wall of official impunity.

The government convened an unprecedented commission of inquiry, where the police version of events completely unraveled. This month, Ibrahim, 44, and four other police officers are scheduled to go on trial on charges of culpable homicide.

'It's Getting Worse'

Nigeria has a history of brutal military and police behavior, ethnic divisions and economic inequality. In the six years since democracy replaced military rule, President Olusegun Obasanjo has sought to tackle corruption, liberalize the economy and elevate Nigeria's international profile.

But in that time, both violent crime and police abuses have worsened, Nigerians say. The size of the police force has more than doubled, but training remains poor and investigative tools such as fingerprinting and autopsies are uncommon. Even critics acknowledge that brutal police tactics are accepted, perhaps even expected, by Nigerians frightened of rising crime.

"One of the lasting consequences of military rule is it has made society a lot more violent," said Joseph Chuma Otteh, executive director of Access to Justice, a rights group in Lagos. "It's getting worse. It's just become a way of life."

Human Rights Watch, the New York-based group, issued a report in July describing torture and killings as routine in Nigeria's police stations, many of which are equipped with rooms grimly outfitted to extract confessions. Dozens of victims reported beatings, electric shocks and rape. One said a police officer inserted a broom bristle into his penis.

The report also said that the number of people reported by police as "killed in combat" had grown from 834 to 3,100 between 2000 and 2003. The United Nations has appointed an official to investigate growing allegations of unchecked police killings.

"Simply because they have guns in their hands, they kill," said Lawrence Ogbonna, 31, whose younger brother Paulinus was one of those killed June 8.

Nigerian police officials initially defended Ibrahim and the other officers, but they no longer dispute the basic facts. Ibrahim and four others are facing criminal charges. A sixth escaped from police custody in mysterious circumstances. A seventh, who had cooperated with the attorney for the victims' families, was fatally poisoned shortly before he was to give testimony.

The president, Obasanjo, condemned the killings in August, saying, "The full weight of the law will be brought to bear on all who are found to have been involved in the perpetration of this most heinous crime."

But officials still dispute the Human Rights Watch report and any suggestions that a culture of police brutality exists.

"There's bound to be one or two cases," said a police spokesman, Haz Iwendi. "We have been a victim of media hype."

To some Nigerians, the serious official handling of the case -- known as the "Apo Six Killings" for the gritty suburb where most victims lived -- has become a sign that democratic systems finally are taking hold here after decades of dictatorship. To others, though, it has made clear how far Nigeria still has to go in entrenching the rule of law.

"If there was no protest," said Damian Ugwu of the Civil Liberties Organization in Lagos, "the Apo killings would have been just one of the numerous cases we have every week."

Pressure for Action

Apo surrounds a stretch of highway lined with steel shipping containers that serve as informal auto-parts shops. The dealers, young men from the minority Igbo tribe, spend hectic days haggling over used Mercedes hubcaps and fuel pumps. Except for Arebun, all the victims worked there. Most lived in squat concrete housing blocks clustered behind the row of containers.

But on the night of June 8, the friends had something to celebrate: the arrival of Ifeanyi Ozor's fiancee, a student, for a visit from Lagos. The group of six left Apo about 7 p.m. in a borrowed gray Peugeot. Five were never heard from again.

Edwin Meniru's telephone rang about 1 a.m. The caller was Anthony Nwokike, 23, a friend of Meniru's younger brother Chinedu. Nwokike was in the car that had been stopped at the checkpoint. Speaking rapidly, he said Ozor, the driver, had been shot in a confrontation with the police and that Chinedu, 21, was wounded but alive.

Then the phone went dead, but those few words galvanized Meniru into action. He immediately started getting word to other dealers of auto parts in Apo. The next day, when a truck carrying six corpses appeared at a cemetery there, the dealers became suspicious.

They were told the bodies were those of armed robbers, but when one young man pulled back a cloth, he recognized Ozor. Meniru arrived soon after to identify his brother's corpse, with bullet wounds in the right thigh and stomach.

"His bag and his clothes are still in my house," the burly man said in an interview afterward. His eyes were wet, his face pinched in grief. "It's very terrible."

In a rage, dozens of young men seized the truck, with the bodies still in the back, and pushed it to the Apo police station, which they set on fire. Police fired into the crowd, killing two rioters, according to witnesses and police testimony. The police reclaimed the original six bodies and buried them in another district, but news reports of the incident piqued public attention.

Although the violence subsided, the pressure for official action did not. The auto-parts dealers wrote a formal letter demanding an inquiry. The victims' families hired an aggressive lawyer, sued the government for damages and spoke to the press. They also went to court to demand that the bodies be exhumed for autopsy and that the police be brought to trial.

The police continued to stonewall, but by the end of June, when the officer who had promised to reveal the truth was poisoned, the political spotlight had grown too bright to ignore.

In testimony before the independent judicial commission, several officers recanted earlier statements and revealed the facts, which were bolstered by the belated autopsies, ballistics tests and other evidence.

Ibrahim, 44, blamed the deaths on the other officers, but their testimony pointed to him as the shooter. There was confusing evidence suggesting possible motives: that Ibrahim had made romantic advances to Arebun, or that his BMW had been scratched while blocking the victims' car, or that Ozor had slapped him in a moment of foolish bravado.

The victims' families have asked authorities to publicly acknowledge that the victims were not robbers, to provide them with a proper reburial and to pay about $714,000 in compensation for each of the dead.

They are also seeking the death penalty for the officers, hoping it might deter others from abusing their power. And, as a final reminder, they have asked that a thoroughfare in the capital be renamed "Apo Six Street."

Edwin Meniru received crucial call after June shooting at checkpoint. Danjuma Ibrahim, a police officer, is lead suspect in the slaying of six.