Ishaq Billa was not the chief suspect in the crime, in which runaway street children in one of the capital's poorest districts were apparently lured to the home of the killer and photographed, then sexually abused before being strangled with chains. But he was suspected of having supplied acid to the self-confessed killer, 40-year-old Javed Iqbal, who has yet to be caught. Iqbal dissolved the corpses of at least some of his victims in acid before disposing of them.
Ishaq Billa, arrested as a suspected accomplice, was being interrogated in Ravi Road police station when he died. Police said he committed suicide, but local news reports claimed that his body bore marks of torture.
Before these events, more detail was emerging about the man behind a string of crimes that has shocked Pakistan far more profoundly than the military coup in October.
It was last Saturday that police received the letter from Javed Iqbal confessing to what he claimed to be the murders of 100 children. "I have killed 100 children, all boys," he wrote, "and placed their bodies in acid-filled drums ... In terms of expense, including the acid, it cost me 120 rupees [pounds 1.50] to erase each victim."
The letter led police to a grim flat in an alley a stone's throw from the police station in the seedy outskirts of Pakistan's most elegant and historic city.
There, besides the drum filled with hydrochloric and sulphuric acid, which was found to contain the meagre remains of three children's bodies, there were placards neatly pinned to the walls, giving more details of his deeds, a list of his victims, annotated with comments on their appearance and the date of their murder, sackfuls of clothes, and photographs.
It was only after killing 43 children, Iqbal wrote, that he had the idea of taking photographs before killing them, to make the record of his murders fuller. The notes accompanying the list of names display a positively bureaucratic attachment to factual detail.
"Victim 87," he wrote, "is Mohammad Imran, aged 15, son of Talib Hussain, district Bahawalnagar, house located next to animal hospital. Father makes wooden cots. Colour wheatish to fair. Health very good. Face beautiful. Cheeks full. Killed on November 11 1999, 7am."
The placards were similarly matter-of-fact, worthy of a functionary in Belsen or Auschwitz. "The five sacks lying in the corner of this room contain the clothes of 100 victims, while the remaining three contain 85 pairs of shoes belonging to them," one of them read.
In the scale of Iqbal's crimes, the insolence of his confession, as well as in the "suicide" of his alleged accomplice, it is tempting to see reflected not merely one man's psychopathy, but also the corruption and decadence of Pakistan's police and civil society as a whole.
Javed Iqbal, after all, was not unknown to the authorities. Local newspapers have reported that he was caught sodomising young boys as long ago as 1985. In 1990, three complaints were lodged against him for sodomy, but he was never convicted.
But then it would not have been difficult for a man such as Javed Iqbal to escape justice. As the painstaking documentation of his crimes attests, he was an educated man: a chemical engineer by profession. By the standards of the other inhabitants of the alleys around Ravi Road, he was also wealthy. For the rich and educated in the subcontinent, nothing is easier than to buy one's way out of the net of justice.
Iqbal, who claimed feebly in his confession that the crimes were to avenge minor wrongs done to him by the police, found his victims among the runaways who haunt Ganj Baksh, a huge Sufi shrine near his flat. For a rich man, nothing would have been simpler than to lure such hapless children home with offers of food or money.
Rudyard Kipling's great novel Kim was partly set in Lahore; its hero just such a harum-scarum youngster, surviving among the low life of the old city. But the low today is lower, and the old checks and safety nets of a homogeneous society are gone. Dozens of desperate parents, wailing, beside themselves with grief as they pawed through the mounds of dirty clothes retrieved from Iqbal's murder house, bear witness to that.
In his letter, Iqbal claimed that now his work was done he planned to drown himself in the Ravi River, which runs through Lahore. The police, however, are sure he is still alive. "He is a very clever man," said Malik Muhammad Iqbal (no relation), the regional head of police. "He is enjoying his fame. He is reading the newspapers."