The family of Lockerbie bomber Abdelbaset al-Megrahi will launch a bid to appeal against his conviction within a fortnight.
Lawyer Aamer Anwar confirmed files will be handed to the Scottish Criminal Cases Review Commission (SCCRC).
The SCCRC will decide whether there are grounds to refer the case to the appeal court.
Megrahi's widow Aisha and son Ali met recently with Mr Anwar.
It is believed they will present concerns over the evidence which convicted the Libyan, including that given by Maltese shopkeeper Tony Gauci, who died last year.
Megrahi was convicted in 2001 of the 1988 atrocity which killed 270 people.
He was jailed for 27 years but died of prostate cancer aged 60 in 2012 after being released on compassionate grounds in 2009.
Megrahi lost an appeal against his conviction in 2002, with the SCCRC recommending in 2007 that he should be granted a second appeal.
He dropped the second attempt to overturn his conviction in 2009, ahead of his return to Libya.