In the fourth of a series of articles looking at policing in Nigeria, the BBC's Andrew Walker asks what happened to the "Apo Six", the most infamous case of extra-judicial killing in Nigeria's history:
The pictures are truly gruesome - we cannot publish them.
Lawyer Amobi Nzelu spreads the glossy prints out on his desk, covering it with horror.
There is nowhere else to look except at the bodies.
There is a close-up of a face, gaping exit-wound at the temple.
Limbs and torsos covered in blood.
Dead eyes stare upward.
"This is a human being," he says.
"Look what they did."
The bodies belong to six young Nigerians killed by the police.
Ekene Isaac Mgbe, Ifeanyin Ozor, Chinedu Meniru, Paulinus Ogbonna and Anthony and Augustina Arebu were killed on 7 and 8 June, 2005.
The police tried to say they were armed robbers who had opened fire first.
But a judicial panel of inquiry set up by former President Olusegun Obasanjo rejected the police's story and the government apologised on behalf of the police for their killings.
The government paid $20,300 (£13,800) compensation to each of the families.
It recommended the officers be arrested and face a criminal trial.
But nearly four years since the night the Apo Six were killed, the trial has got nowhere.
The public has almost forgotten the case is still going on.
Danjuma Ibrahim, the senior police officer accused of ordering the killings, lives free on medical bail.
And the families of the dead have all but given up on justice.
Elvis Ozor is the younger brother of Ifeanyin Ozor.
Like his brother, he works as a spare car parts merchant in the Apo mechanics' village, south of the capital, Abuja.
It is a kind of shanty-town of sea crates and workshops where five of the Apo Six worked.
APO SIX TIMELINE
7 June 2005:
Apo Six meet Danjuma Ibrahim at a party
Four shot at police roadblock
Ifeanyin and Augustina seen alive at Garki police station
Police try to bury six in a cemetery near Apo
Two days of rioting in Apo and Garki districts
Police begin internal investigation
President Obasanjo orders inquiry
Police witnesses testify the six were slain in cold blood
Police armourer admits weapons planted on bodies
Court rules the suspects will face trial
Bodies buried by families
18 January 2006:
Trial of police officers begins
Danjuma Ibrahim released on "exceptional and special" medical bail
This is a tight-knit community, mostly of ethnic Igbos from Nigeria's south-east.
On 8 June 2005 the Apo mechanics found the police burying their friends in a cemetery that, by chance, was near their workshops.
"My friend was going to the bush, to go to the toilet, when he saw the police digging a hole and preparing to bury some people," Elvis says.
"They recognised my brother. When the police said they were armed robbers, no-one believed them - they knew my brother was not like that."
"When I arrived at work, word had spread, but I didn't know. I arrived and everyone was looking at me," he says.
The story was out, and an angry mob gathered.
There was a riot in Apo and the police shot two more people dead.
Unlike any other case of suspected extra-judicial killing in Nigeria, some of the police broke ranks and turned on the senior officer involved.
The other five officers accused of the murders and eight more police witnesses have testified that Danjuma Ibrahim ordered the killings.
During the judicial panel hearings, some Igbo police officers fed information to Mr Nzelu, who represented the families of the Apo Six.
The panel heard that the six were at a nightclub in Abuja's Area 11 when Mr Ibrahim - then off duty - propositioned Augustina.
She turned him down, according to the testimony of Ifeanyin Ozor's friends.
Mr Ibrahim went to a police checkpoint at the end of the street and told officers there were a group of armed robbers in the area.
When the six young people came in their car, he drove into them, blocking their way and ordered the police officers to shoot.
Danjuma Ibrahim was a high ranking police officer in the Nigerian Police
Ifeanyin called his friends after he survived the first burst of gunfire, they testified.
Who actually fired the shots is still disputed by Danjuma Ibrahim's lawyers, but four of the six were killed there, the prosecution says.
Ifeanyin and Augustina were taken to a police station.
Officers called Augustina's family to demand a 5,000 naira (then $43, £22) ransom to let her go, according to a report by the UN special rapporteur on extra-judicial execution.
Her family could not raise the money.
They were taken to a piece of rough ground outside town where they were executed, police officers testified at the criminal trial.
Augustina was strangled.
Then the police planted guns on the bodies of all six of the bodies and pictures were taken of them in the grounds of a police station by a police photographer.
At the criminal trial, Mr Ibrahim's lawyers maintained that the Apo Six fired first.
He says all of them were killed in the gun battle, and a "home made" pistol and a shotgun were found in the car.
His lawyer Hyeladzira Nganjiwa says the prosecution dropped charges against some police officers in return for them changing their testimony.
Mr Ibrahim is the fall guy in a government plot to sweep the incident under the carpet, he said.
"I could never have done what they are accusing me of," Mr Ibrahim told the BBC outside the Abuja court where he is being tried.
He was released on medical bail in 2006, after his lawyer said he had a heart condition.
The five other accused - one of whom is now dying of Aids, according to his lawyer - remain in police custody.
That trial has been going on for almost three years.
After hearing the testimony of eight prosecution witnesses, the defence is now cross-examining the first.
Lawyers say the case is being stalled so it will eventually be forgotten, and the charges dismissed.
In this case people accepted the victims were not armed robbers because they came from a close community.
But in other less high-profile cases, the public turns a blind eye to police killing, human rights advocates say.
The reluctance to punish police officers "emboldens" other officers to kill, says Eric Guttschuss of Human Rights Watch.
But the police say a great deal has changed since Apo Six case.
"The police have a higher respect for human rights than before," says spokesman Emmanuel Ojukwu.
"I am not aware of any recent cases of extra-judicial killing."
Mr Guttschuss of Human Rights Watch, which tracks alleged cases, disagrees.
"Extra-judicial killing in the police remains a shockingly common occurrence."
He says the police lack the capacity to properly investigate crimes, and because of the pressure from society to deal with violent criminals, they simply dispose of suspects without the encumbrance of trials.
"[A] Nigerian's guilt or innocence is immaterial," he says.
Elvis Ozor says he has given up on the judicial system.
"When Danjuma was released, I forgot everything about the case."
"The only way justice will be delivered is from God."