Key witnesses lied to protect the man convicted of murdering four members of the same family in Clydach, south Wales, a leading detective has said.
Det Supt Martin Lloyd Evans said David Morris, 44, would have been caught sooner had they come forward.
Mandy Power, 34, her children Katie, 10 and Emily, eight, and their grandmother Doris Dawson, 80, were bludgeoned to death in their home in June 1999.
It was 19 months after the murders before police arrested Morris.
At a press conference following the verdict, police said they would be investigating the testaments of Mandy Jewell and other witnesses who gave Morris false alibis.
Mr Evans said the crime scene on Kelvin Road, where Mandy Power and her family were found murdered and their home set alight, was so devastating, detectives believed the answer would be there "very quickly".
He also thought more witnesses would have come forward with vital clues because Clydach was such a close community.
David Morris was among 50 people police initially wanted to speak to
"Had they (some witnesses) come forward this case would never have taken almost two years before the arrest, " he said.
"But these individuals kept that information to themselves and did not tell anybody."
Before Morris was charged, police had arrested and put on bail Mandy Power's lesbian lover Alison Lewis, her then husband Stephen and his brother Stuart.
This led to criticism of the way the case was handled. But Mr Evans denied police had ignored initial suggestions from people in the community that Morris was the guilty party.
"We spoke to him within the first three or four days of the murders. Yes, he was linked with Mandy Power in the past but there were lots of people in this investigation that we needed to speak to," he said.
"There were 50 (police wanted to talked to) at one stage and David Morris was one of them. The initial investigation was never centred on one individual.
"But can I just say that a lot of people have lied for David Morris and protected him in those early days."
A key piece of evidence in the case to convict Morris was a gold chain, covered in Mandy Power's blood and found at the murder scene. Initially, Morris had denied the chain was his.
Then Morris changed his story and said he had left the chain at the house the morning before the murder when he said he had sex with Ms Power.
However, the prosecution told the jury that phone records from Morris' flat proved he could not have been there at that time.
Mr Evans said these records played a vital role in the re-investigation detectives undertook before Morris' retrial.
Mandy Power's blood was found on Morris' gold chain
They helped detectives prove Morris could not have left his chain at Mandy Power's home under innocent circumstances.
When asked to describe David Morris, Mr Evans said he was "extremely devious and very cunning".
"I am convinced he thought he had got away with it," he said.
"From the very day he committed this crime he was working on his defence and was expecting, at some stage, a knock on the door.
"He changed his evidence no end of times. I believe 19 times in one interview he said 'I am telling the truth this time' and clearly he wasn't.
"At this trial he has lied yet again but he has been caught out with these lies."