Police believed a new defence witness in appeals by two men jailed for murder may have been held and threatened at gunpoint, a court has heard.
The officer, who headed the inquiry, rejected claims that the man was arrested in a last-ditch attempt to rescue his case.
Constable Stephen Carroll was shot dead as he responded to a 999 call in Craigavon in March 2009.
John Paul Wootton, 22, from Collingdale, Lurgan, and Brendan McConville, 42, of Glenholme Avenue, Craigavon, are serving life sentences for killing the police officer at Lismore Manor, Craigavon and are appealing their convictions.
Det Ch Insp Richard Harkness told the appeal court: “I had reason to believe he (the witness) was under immense pressure from persons who would not have the interests of justice at heart and would not think twice about inflicting serious violence on people if they didn’t get their own way.”
The officer denied allegations the man was held and questioned in a bid to “nobble” him and sabotage attempts by McConville and Wootton to overturn their convictions.
During a detailed cross-examination, he said it was untrue that he had overstepped the mark and turned his investigation into a “mission”.
Central to the prosecution case was the evidence of a man identified only as Witness M who claimed to have seen McConville in the area around the time of the killing. However, this man’s father has testified to the Appeal Court that his son was a compulsive liar and Walter Mitty-type who could not have been there. The new witness was arrested and detained overnight on suspicion of withholding information before being released without charge. He said he was never coerced, threatened or forced to make an affidavit undermining his son’s credibility.
When asked by the defence that covert surveillance of this man’s home and a bar failed to back up police suspicions that he had been held against his will, the detective said he had other information prior to the operation indicating the man had been held against his will.