A note attached to a fake bomb left at Dunedin Airport was written by the security staff member on trial, a forensic expert says.
It was one of the 20 pieces of circumstantial evidence Crown prosecutor Richard Smith said proved the guilt of 32-year-old Preetam Prakash Maid, who has been in the dock at the Dunedin District Court for more than two weeks.
But defence counsel Deborah Henderson argued there were plenty of others who had the opportunity to commit the crime.
While the police handwriting expert last week told the jury it was impossible to definitively say a cryptic note attached to the hoax explosive device was written by the defendant, she believed it was his.
Smith, during his closing address yesterday, compared the note - which read "A: Alpha, B: Birds, C: Crash, D: Dunedin, E: Emergency, F: Fools" - with examples of Maid's handwriting.
He pointed out the R "like a fish", the U "like a horseshoe", the M with "a subtle hook" and the S with "unusual balance".
Henderson pointed out, though, that Maid had been the only staff member whose handwriting was assessed.
The Crown case is that Maid planted the bomb during his perimeter patrol as an aviation security officer on March 17 last year – just two days after the Christchurch mosque attacks – to push his agenda for heightened security at the airport.
Smith said there would have been an associated benefit to him.
"He'd get more work, more hours and more pay," he said. "Young man, young family, baby on the way."
Within half an hour of returning home from his shift on the day of the incident, the court heard Maid had contacted five media organisations to highlight the security breach.
Henderson called the point "a red herring" and urged the jury to focus on the identity of the hoaxer.
The police's first thought, she said, was that someone had jumped a fence and placed the bag beside the hut.
There had been reports of cars parked in the vicinity that day and there was a "scruffy" man seen on foot around the premises.
None of them were found by police.
Earlier in the trial, the court heard from a witness who spoke to the defendant the following day.
Maid said he had struggled to sleep the previous night because of "what was in that ****ing bag".
Smith told the jury that at that stage, the defendant would have had no idea what was in the bag – unless he planted it.
But that was disputed by Henderson, who said her client had been told at that point.
The contents of the laptop bag found beside a small building past the north end of the runway pointed to Maid as the culprit, Smith said.
A Soda Stream butane canister, cellphone, battery, wires and bubble wrap could all be traced to the dangerous goods store to which the accused had access.
Swipe-card records also put him in that corridor for two periods of 10 minutes that day.
In a couple of months leading up to that, Smith said, Maid had only been in that area twice, and fleetingly at that.
CCTV captured Maid taking tape from a reception area and later returning it.
The Crown said that was him assembling the fake bomb, but Henderson said he had actually been fixing a fish tank in the security office block.
Smith accepted it had been an information-dense trial, which had generated 1000 pages of transcript.
He simplified it, however, as a "whodunnit" and urged the jurors to use their common sense.
"Like a jigsaw, you will begin to see the picture reveal," he said.
Judge Michael Crosbie was due to sum up the case this morning before the eight women and three men of the jury deliberate.
The charge under the Aviation Crimes Act carries a maximum penalty of five years' imprisonment.