A top forensic scientist has admitted Omagh bomb trial evidence could have been contaminated with Sean Hoey's DNA when it was examined in a laboratory.
Twenty-nine people died in the Omagh bombing
The court heard tape seized by police from his home in 1998 was compared with tape taken off bomb timers.
Forensic scientist Dennis McAuley said they did not protect against dangers of contamination as the items were not suitable for DNA analysis at that time.
Mr Hoey denies 58 charges including the murder of 29 people in Omagh in 1998.
The rolls of tape were seized from the accused's home in September 1998, just over a month after the Omagh bombing.
Forensic scientists compared them with tape taken off bomb timers in a series of attacks that year.
They did not find any matches but when comparing them, they were not protecting the items from potential DNA contamination.
Mr McAuley admitted there was the real possibility of Mr Hoey's DNA being transferred onto the evidence.
Low copy number DNA - a technique whereby DNA profiles can be obtained from samples containing only a few cells - is an important part of the prosecution case.
The judge, Mr Justice Weir, has asked Mr McAuley to prepare a new statement to take into account some of these issues.
It will be given to the court when it resumes on 7 November after a one-week break.
It was also revealed that the police have lost five bomb timers - some used in attacks in 1998.
The timers are similar to the ones used in the series of attacks that the accused is charged with, and could potentially have been important evidence.
The case continues.