Robert Hamill, a Catholic aged 25, was beaten by the gang in Portadown, Co Armagh, in April 1997.
He never regained consciousness and died in hospital.
District Judge Peter King said the evidence provided to the court was insufficient to put the accused on trial.
A Courts and Tribunals Service statement said: "In giving judgement District Judge King found that the evidence provided to the court was not sufficient to put the accused on trial."
The case involved a police officer allegedly tipping off a former suspect.
Mr Hamill, a father-of-three, suffered serious head injuries and died 11 days after the attack.
His murder was one of four cases examined by retired Canadian judge Peter Cory following claims of security force collusion in the killings.
Allegations that police failed to intervene to help Mr Hamill were the subject of a subsequent public inquiry.
The Magistrates' Court in Craigavon on Wednesday declined to return the defendants - police reserve constable Robert Atkinson and his wife Eleanor Atkinson who live in Brownstown Road, Portadown, and Kenneth Hanvey who lives in Derryanvil Road in the town - to the Crown Court on charges connected to the murder of Mr Hamill, the Courts' Service statement said.
They were accused of offences including conspiracy to pervert the course of justice.
This is the second time the evidence surrounding the credibility of a key witness has been found wanting.
In March, a higher court in Belfast quashed a decision by the magistrates' court to stay proceedings and directed that a new preliminary inquiry, which assesses the evidence before the case is sent for trial, begin afresh with a different judge.
This new inquiry commenced last month.
According to the court statement, a phone call was made from reserve constable Atkinson to the home of a former suspect in the killing during which he advised him to destroy the clothing he was wearing at the time of the incident and later, kept him up to date as the police investigation progressed.
Mr Atkinson claimed his phone had been used by another man. However, his former wife Andrea Jones became a key witness when she contradicted this.
District Judge King said he found Ms Jones to be "an entirely unreliable and utterly unconvincing witness".
District Judge King said that he was not able to attribute any degree of credibility to any portion of her deposition. He said that the evidence was not sufficient to put the accused on trial and he declined to return them to court.
Court Service statement
"She was evasive, obstructive and untruthful, peppering her evidence with inconsistencies and outlandish assertions of having no recollection of pivotal moments in her life," the judge said.
She changed her account to police and provided facts which the judge believed were designed to enhance the veracity of the statement.
She referred to watching a pay per view boxing match when no such boxing match had been screened at that time.
She also reported receiving a threatening letter from the Loyalist Volunteer Force paramilitaries while living in Wales, although the fact that it had been processed in Chester prompted concerns that she had posted the letter to herself.
The Courts Service statement added: "District Judge King discharged each of the accused in respect of all matters before this court."
After Judge King's ruling Mr Hanvey's solicitor Richard Monteith, in a statement, alleged that the decision to prosecute was "politically motivated" and that this was the third time that his client's position had been vindicated.
He said he had "some difficulty" in understanding why the Public Prosecution Service could let this case go forward for a third time in 2014 as "it should have been clear to any independent and clear thinking prosecution authority that this case was not fit to come before court."
"Accordingly the decision wasted a significant amount of court time, a large amount of public money and resources at a time when the Department of Justice was making substantial cuts to save money."