Lundy is appearing before the Court of Appeal in October, maintaining again that he did not murder his family.
In the lead-up to the appeal Lundy has released three handwritten letters from prison.
The letters were published on the Factual Trust website.
Factual is an acronym of For Amber & Christine - Truth Uncovered About Lundys.
The letters were penned on July 19 and 20 and August 2.
In the most recent letter Lundy claims he was given "ambiguous" information from police about their case against him.
He listed the differences and changes between the evidence in the first and second trials including evidence around the time of death of his victims, driving speed and times, eyewitnesses and fingerprints.
The letters are signed off "yours in innocence, Mark Lundy".
In his first script Lundy says he respected the jury's opinion, but disagreed with them on their verdict.
"It is wrong and as a believer in the truth I will always fight against it - any innocent man must," he wrote.
"I am lucky to have wonderful friends and a great legal team helping with my fight."
He said his upcoming appeal was his "latest attempt at obtaining justice".
"It is a difficult road to travel, but in the name of truth, it is one that I definitely must travel," he penned.
"Please remember that there is a very good reason for fighting my conviction.
"I did not and could not commit such a heinous crime - especially to my beloved Christine and Amber."
