The defendant was drinking and dancing at a social gathering onboard the Royal New Zealand Navy ship in February last year when they fell and hit the back of their head on a wooden coffee table.
After stumbling into a different mess room, the officer fell again and hit the back of their head a second time against a firm sofa.
While being escorted to the bathroom, the defendant asked a junior colleague, Able Logistics Supply Specialist PJK Maka why he was "eyeing" them and placed a hand - without force - on his throat, with his back against the wall.
Maka said the throat incident happened quickly. The defendant did not use much force, he said, and his breathing was not impeded in any way.
The defendant did not deny the incident happened but pleaded not guilty at the start of the hearing, saying they had no recollection of the incident.
"I was in shock, disgusted, mortified really," the accused said in an interview recorded 10 days after the incident and played in court on Monday. "Why are people saying I did something? I don't remember it."
"In my head that's a serious offence, any type of assault is serious," the defendant had said, breaking down during the interview.
Before the mistrial was called, the court on Tuesday morning heard expert testimony from neurospsychologist Dr Jon Nuth, who assessed the defendant's two head knocks before the alleged assault as "significant blows" to the back of the head.
An officer who witnessed the first fall said there was a loud bang when the defendant hit a wooden chest that served as a coffee table. He said the defendant was vibrant and lively before the fall, but became dazed, unresponsive, and unstable afterwards.
Another witness described the defendant's second head knock - against a firm sofa - as a "sharp jab" to the back of the head from a "16-ounce boxing glove".
The case is now pending the next steps of the prosecution.
