The man accused of murdering 29 people in the Omagh bombing has claimed police were on a witch hunt to "cover up their own inadequacies".
A court artist's drawing of Sean Gerard Hoey
Sean Hoey from Jonesborough, County Armagh, denies a total of 58 charges.
Hoey, 37, said if his DNA was on any evidence it was either there innocently or "planted" by police "or some other agency the police are using".
The claims were made during police interviews which have been read out at his trial.
Earlier, the trial heard that an investigation into how bomb timers, linked to the Omagh trial, were lost up to eight years ago, only began a couple of weeks ago.
The lost timers had been found at a number of attacks in 1998 and were lost as early as 1998.
The Forensic Science Service in Northern Ireland was responsible for tracking the timer power units.
Jim Speers,was questioned about the bomb timer units
In court, its acting operations director, Jim Speers, was questioned about whether their disappearance had ever been investigated.
Initially, he seemed to indicate that an investigation was under way, but he said he had not spoken to anyone about it.
However, during questioning by the defence, Mr Speers paused and asked the judge if he could consult the prosecution lawyers.
Mr Justice Weir looked surprised and told him to answer the questions.
He then revealed that he himself had asked for the review - and that he had only done so a couple of weeks ago - that would have been after the issue of the missing timers had been raised in the trial.
More details of why accreditation was suspended at forensic laboratories in Northern Ireland was also revealed.
The accreditation service had a number of concerns including administrative errors and they discovered equipment had not been properly checked.
A subsequent review by a consultancy firm found dozens of what it described as significant "non-conformities" or mistakes.
However, Mr Speers said that none of the errors had a risk "of an unsafe conviction or a miscarriage of justice".
The trial will resume on Thursday when the prosecution is expected to complete its case.