The Delhi High Court on Wednesday sentenced to life imprisonment 16 then personnel of Uttar Pradesh's Provincial Armed Constabulary (PAC) for killing 42 people in 1987 in Meerut in what came to be known as the "Hashimpura massacre" .
In doing so, the court set aside a March 2015 trial court verdict acquitting the 16 men after giving them the benefit of doubt.
There were originally 19 accused but three died during the prolonged trial. All the 16 are now retired.
Vibhuti Narain Rai, the then Superintendent of Police in Ghaziabad who registered the first FIR in the case on the night of May 22-23, 1987, told IANS: "This was the first and biggest custodial massacre in independent India.
"There was a similar carnage in Nellie but that was not in police custody unlike this."
The victims, all Muslims, were picked up from the Hashimpura neighbourhood by the 41st Battalion of the PAC during a search operation, taken away in trucks, lined up and shot dead in cold blood.
The charge sheet was filed before the Chief Judicial Magistrate in Ghaziabad in 1996.
The case was transferred to Delhi in September 2002 on the Supreme Court's orders following a petition by the families of the victims and the lone survivor.
A sessions court here in July 2006 framed charges of murder, attempt to murder, tampering with evidence and conspiracy against all the accused.
Rai, who later brought out an investigative book on how the massacre, recalled: "It was one and a half hours later that we got wind of the killings by the PAC. We could rescue one person, Babudin. It was on his description of the massacre that we registered the FIR."
He said the Muslim youngsters were randomly picked up from the Hashimpura locality, taken through Ghaziabad and thrown into water canals after being indiscriminately shot at.
"It was a chilling, shocking massacre. Before I could launch my investigation, the case was handed over to the Crime Branch of the CID," said Rai, who retired as Director General of the Uttar Pradesh Police (Vigilance) and later served as Vice Chancellor of the Mahatma Gandhi Hindi Vishwavidyalaya at Wardha.
(With inputs from agencies.)