Relatives of a man who was murdered in his own home were told of his killer's release from prison on the anniversary of his death, MSPs have heard.
Scottish Conservative leader Ruth Davidson said Michael Mosey's relatives were given the news in a letter from the Scottish Prison Service (SPS).
Just six weeks earlier, the family had wrongly been told that the killer would not be allowed out of prison.
First Minister Nicola Sturgeon said the case was "unacceptable".
The first minister outlined plans to improve the information and support available to victims when prisoners are released in her programme for government earlier this week.
But Ms Davidson said Mr Mosey's case highlighted the need for "decisive action" rather than merely "warm words" to ensure victims have more rights than criminals.
The Conservative leader said she had been contacted over the summer by relatives of the former policemen, who was bludgeoned to death in his own kitchen near Harthill, West Lothian, in August 2006.
The killer was sentenced to 18 years in jail, which was then reduced to just 13 years on appeal, Ms Davidson said.
She added: "This June, after being told of rumours that he was to be released early, they wrote to the SPS and were told that that wasn't the case.
"But then just six weeks later they received another letter informing them that he had in fact already been approved for temporary release. A letter that coincided with the anniversary of Mike's murder.
"The family have been left traumatised and they feel that the system has totally let them down."
The Conservatives have backed the Michelle's Law campaign which is named after teenager Michelle Stewart, who was murdered by her ex-boyfriend in 2009.
The following year, John Wilson was given a sentence of at least 12 years for stabbing Michelle to death near her home in Drongan, Ayrshire.
But her family have been told by the SPS that Wilson has been approved for first grant of temporary release after just nine years.
Her family have been campaigning for victims and their families to be given a bigger say in how decisions such as this are made, and for there to be an explicit requirement that their views to be taken into account when parole and early release are considered.
They also want the creation of "exclusion zones" where offenders cannot go during early release, and improvements to the victim notification scheme so families are given reasons for an offender's release, and are allowed to make representations in person.
Ms Davidson said the Stewart family believed the plans outlined by Ms Sturgeon on Tuesday contained "lots of warm words but nothing concrete".
She called for Ms Sturgeon to clarify exactly how and when improvements will be made to the parole and early release processes.
Ms Davidson said the relatives of Mr Mosey and Ms Stewart, and others like them, are "just asking to be heard when the killers of their loved ones are being released".
She added: "They feel that criminals have more rights than victims and they want the law changed so that victims are put at the heart of the justice system, which is where they should be."
Ms Sturgeon responded by saying Justice Secretary Humza Yousaf, who recently met Ms Stewart's family, would also be happy to meet relatives of Mr Mosey.
She added: "We're actively considering the Stewart family's proposals, and indeed other calls for improvements, in detail.
"We're already in discussion with the parole board on further reforms and possible development of their rules of procedure, and of course that has to include whether any changes are necessary following the Warboys case in England."
Ms Sturgeon said the government would consult on changes by the end of this year and early next year.
She added: "We do think we need to look at what more needs to be done to ensure that victims and families of victims are given proper notice and, where appropriate, are properly consulted when these decisions are taken."