London, England (CNN) -- Scottish prosecutors are conducting a further review of the evidence related to the Lockerbie bombing, prosecutors have told families of victims from the United Kingdom.
In an excerpt from an e-mail from Scottish Crown Prosecution Service to the victims' families, provided to CNN by one victim's family member, prosecutors say the investigation is still ongoing.
"Throughout the investigation we have, at various times, taken stock of the evidence as a whole with a view to identifying further lines of inquiry that can be pursued," the e-mail said. "Now that the appeal proceedings are at an end, a further review of the case is underway and several potential lines of inquiry, both through a 'desktop' (paper) exercise and consultation with forensic science colleagues are being considered."
It continued: "Please be assured that this is not simply paying lip service to the idea of an 'open' case."
The December 1988 bombing of Pan Am Flight 103 over Lockerbie, Scotland, killed 270 people. One person, Abdelbaset al Megrahi, has been convicted for the bombing and was sentenced to life in prison.
In August, Scottish Justice Secretary Kenny MacAskill released him on compassionate grounds because he had been diagnosed with cancer. MacAskill had authority over al Megrahi because the bomber was serving his sentence in Scotland, which runs its own judicial system.
Al Megrahi, 57, currently is being treated in a hospital in Libya.
On Sunday, a group of victims' families launched a campaign to get the British government to open a public inquiry into the case. The group handed over a letter to 10 Downing Street, calling on Prime Minister Gordon Brown to look into the matter.
"The relatives believe that a public inquiry offers the last realistic hope of finding out how and why their loved ones perished," said a posting on the group's blog. "They are worried that without it their chances of learning the truth could end when Megrahi dies."
Pamela Dix, who lost her brother in the bombing, acknowledged that the criminal investigation falls under Scottish authorities but insisted that the British government also had a responsibility.
"While the UK government does not have responsibility for the criminal investigation, it does have responsibility for foreign affairs," Dix told CNN. "The aircraft took off from Heathrow airport, in England, and it just happened to explode over Scottish grounds.
"The previous prime minister, Tony Blair, assured the relatives that he would leave 'no stone unturned' in the efforts to get to the bottom of what happened. Our current prime minister should take forward this commitment."
A spokeswoman for 10 Downing Street acknowledged receiving the letter and said there would be a response, but that "this happened on Scottish soil, thus it is up to the Scottish authorities to handle."
British Foreign Secretary David Miliband on Sunday rejected claims that his government should get involved.
"This is rightly a matter for the Scottish authorities," Miliband said. "We've always said that this was a terrible crime where justice must be done and every avenue pursued. The investigation was never formally closed and that's why it's wholly appropriate that if there are grounds for taking new steps, that they should be taken."
He went on to say that the case was investigated by the Scottish authorities: "It's right that they pursue the investigation on a criminal basis and if there's any suggestion of an inquiry that should be a matter for the Scots, because that's the way our system works. But you can see from today's announcement that the commitment in Scotland remains real in respect of justice in this case and that must be right."
Dix called Miliband's comments "entirely inappropriate" in attempting to shift responsibility away from his government.