The defence team for Sean Hoey is due to begin its case when the Omagh bomb trial resumes this morning.
Mr Hoey (37), an electrician from south Armagh, is facing 56 charges, including the 1998 Omagh bomb, which killed 29 people.
Mr Hoey denies all the charges. His team is expected to take 50 days to complete its case.
Prosecutors have used voice analysis and DNA profiling in an attempt to link the suspect to a string of bombings. They ended their case before Christmas.
Belfast Crown Court judge Mr Justice Weir has dismissed two charges but rejected a defence application to throw the entire case out of court.
Experts have already discredited the DNA forensic technique used to link Mr Hoey to a number of incidents.
The Omagh car bomb exploded on August 15th and killed 29 people, including a woman pregnant with twins, and injured scores more. It caused the single greatest loss of life of the Northern Ireland conflict.