Barry George was acquitted after spending several years in jail
Jill Dando's former agent has said he never believed Barry George was the television presenter's killer.
Jon Roseman told the BBC her murder will be "one of those terrible crimes that will never be solved".
Mr George, 48, of Fulham, west London, was on Friday cleared of murdering 37-year-old Miss Dando, who was killed on her doorstep on 26 April 1999.
He was first convicted in 2001, but a retrial was ordered after doubt was cast on gunshot residue evidence.
Mr George's barrister, William Clegg QC, said on Saturday the prosecution case had been circumstantial, and there was no direct evidence that Mr George was the killer.
He told BBC Radio 4's Today Programme there were lessons to be learned from the case.
"In considering a case of this complexity the police and those responsible for the prosecution need to keep an open mind as far as possible as to who is responsible.... I think they did close their mind after the arrest of Barry George," he said.
In a statement issued through his solicitor Jeremy Moore after Friday's verdict, Mr George said he was "overwhelmed".
He added: "I want to thank my family, my legal team, my medical team and all the people who have supported me at Belmarsh, Whitemoor and Manchester prisons, and all my supporters."
But Mr Moore said: "This is not a time to celebrate. Barry George, an innocent man, has spent eight years in prison for a crime he did not commit.
Barry George's solicitor reacts to the verdict
"Those eight years could have been better served by the police in searching for the real killer."
Mr Moore said he would not be surprised if Mr George sought compensation for the time wrongly spent in jail.
Scotland Yard said it was disappointed by the verdict but respected the decision of the court.
"We will be reflecting on today's verdict and considering how best to proceed," said Simon Foy, head of Scotland Yard's homicide and serious crime command.
The Crown Prosecution Service said Mr George had the right to be regarded as an innocent man, but that did not mean it had been wrong to bring the case.
Jacqui Hames, who served in the Metropolitan Police for 25 years and worked alongside Miss Dando on the BBC's Crimewatch programme, said her thoughts were with Miss Dando's family and friends.
Barry George's sister said she hoped police would relaunch the investigation
"Any result like this is always difficult for family members because it re-opens all the old wounds," she said.
"And that line drawn underneath what happened has now disappeared and there is the prospect of at least a review if not a re-investigation into the case."
Mr George was arrested on 15 May 2000, a year after the shooting in Gowan Avenue.
Forensic evidence about a tiny speck of gun residue found in Mr George's coat pocket after his arrest helped secure his original conviction.
But last year, the Court of Appeal ruled new scientific doubts over the evidence meant the conviction had to be quashed, and ordered a retrial.
During the trial the prosecution portrayed Mr George as a loner and oddball, with a history of harassing women, a fascination with celebrities and an interest in guns.
But the defence portrayed him as a man with epilepsy and a low IQ who was not capable of carrying out a professional-style killing - and it appeared the jury agreed.
Mr George's sister Michelle Diskin, who has led the fight for his release, said she hoped the police would launch a reinvestigation.
"We are really delighted to finally have justice," she said.
"A huge thank you to the jury. They obviously worked very hard to ensure they correctly interpreted the circumstantial evidence in this case.
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