A total of 24 sex offenders are missing in Scotland, police have revealed.
Concerns were raised following the murder of Angelika Kluk
The figure came as the first minister vowed to investigate whether improvements could be made to keep track of sex offenders.
At First Minister's Questions, Jack McConnell said he was "surprised" there was no national missing figure. Police have since collated the full total.
It follows the Angelika Kluk murder case which saw a sex offender employed at a Glasgow church under a false name.
A spokesman said half of those offenders said to be missing were believed to have fled overseas.
Nicola Sturgeon, Holyrood leader of the Scottish National Party, said her inquiries had revealed that neither the Association of Chief Police Officers in Scotland (Acpos) nor the Criminal Records Office kept a central list of sex offenders who had gone missing.
"In the interests of protecting public safety, we should know how many sex offenders are off the police radar screen," she said.
"And the fact that we don't know that represents a worrying gap in our knowledge about sex offenders that the public would expect to be filled."
Mr McConnell said he shared her concern, adding that it was one of the first questions he and Justice Minister Cathy Jamieson had asked in the wake of Angelika Kluk's death.
"We have been surprised to find there is not more detailed information available more quickly," he said.
"We are working with the system to ensure that it indeed does become available."
Scotland has 3,200 registered sex offenders.
Each of Scotland's eight police forces is supposed to have a list of sex offenders who have gone missing in their area, however it has so far proved difficult to compile a national list.
"It should be possible for chief constables at a national level to compile that information into one set of national data," Mr McConnell said.
"We will pursue that matter - but much more importantly, we will pursue the issues of having the right laws in place and the right procedures in place to reassure the public."
Mr McConnell later told Labour backbencher Pauline McNeill, MSP for Glasgow Kelvin, of the "real pain" felt by everyone for Ms Kluk's family.
Nicola Sturgeon said improvements needed to be made
The body of Ms Kluk was found on Friday night at St Patrick's Roman Catholic Church in Glasgow's Anderston area.
Mr McConnell said new provisions brought in this year allowed police greater access to the homes of people on the Sex Offenders Register.
He added that the executive was now considering recommendations in a report by Professor George Irving that there should be a "constant" assessment of people on the register.
The Scottish Conservatives said it was vital that the police did everything in their power to establish the whereabouts of the missing sex offenders.
Margaret Mitchell MSP added that she had tabled further questions asking for more details of who they were and the offences they had committed, in order to establish a profile of each individual at large.
She said: "I would also urge the authorities to let their victims know they are at large, if this has not been done already."
A Scottish Executive spokesman said it did not routinely collate a national number of sex offenders who may have breached conditions as the sex offender scheme was administered locally.
"The police know who the local sex offenders are, where they live and the requirements imposed on them by the court," he said.
He said the information was held on police databases which were regularly updated, including information about breaches.
The spokesman added that all police forces already prioritised warrants, especially if the risk or alleged actions of an individual were serious.