Some 736 images were deleted from a hidden camera found inside a bathroom at the New Zealand embassy in Washington, a court has heard.

But the first video file police recovered from the camera reveals images of a person wearing blue latex gloves hiding the "black box" inside the unisex bathroom's radiator.

New Zealand's former Assistant Chief of Navy is the man accused of planting the covert filming device in the diplomatic building's bathroom during July 2017.

Former Commodore Alfred (Fred) Keating was serving as the senior defence attache to the United States at the time and was stationed in the American capital.

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This week, the former commanding officer of the Devonport Naval Base has been on trial in the Auckland District Court, charged with attempting to make an intimate visual recording of another person.

Today, the jury heard from senior police digital forensic analyst Kerry Baker that 736 files were deleted from the memory card inside the hidden camera.

A further 21 video files were still on the micro SD card, all from July 27, 2017, the same day the camera was discovered.

Most of the still images were associated with the video files, the court heard.

The first video was later played to the court this afternoon and shows a person wearing blue latex gloves positioning the hidden camera inside the bathroom's heater.

The camera is positioned just after 9am Washington time to film those using the toilet.

However, the video does not show the person's face or any other significant identifying features.

Crown prosecutor Henry Steele accuses Keating of placing the camera to covertly film his colleagues at the embassy using the toilet.

"This was not an act of espionage," Steele has said.

Baker also said software from BrickHouse Security, the camera's manufacturer, had been installed on Keating's computer on July 24, 2017, but later uninstalled at 6.47pm on the day the device was found.

Earlier in the trial, Environmental Science and Research forensic scientist Sue Vintiner told the court an "ultra-sensitive" DNA test of the memory card showed a male profile which matched that of Keating's.

The DNA was "10,000 million times more likely" to have come from the 59-year-old than another person with the same DNA profile, Vintiner said.

However, Keating's lawyer, Ron Mansfield, questioned the "low copy number DNA test" used, which has been criticised by some overseas jurisdictions because of a high risk of contamination associated with the test.

Alfred Keating is on trial in the Auckland District Court this month. Photo / Jason Oxenham
Alfred Keating is on trial in the Auckland District Court this month. Photo / Jason Oxenham

Yesterday, the internet search history on Keating's laptop was also revealed.

It had been recovered by a digital forensics officer after police raided the naval officer's home some months after the Washington DC incident.

On July 25, 2017 - just two days before the device was discovered in the embassy bathroom - an internet search on Keating's computer was made for BrickHouse Security.

The Google searches came at about midnight Washington time and included, "Brickhouse camscura modes" and "Brickhouse camscura switch positions".

The laptop was also used to visit BrickHouse Security web pages eight times between March 25 and July 25, 2017, the court was shown.

A further search on Amazon via the search engine Bing for BrickHouse Security was made on July 25, about 20 minutes after midnight.

The style of covert camera, as advertised on Amazon, which was found in the bathroom. Photo / Supplied
The style of covert camera, as advertised on Amazon, which was found in the bathroom. Photo / Supplied

Then on September 17, 2017, the computer software CCleaner was searched and seemingly downloaded and installed, the court heard.

CCleaner is described online as a program which can delete temporary or unwanted files on a computer.

Today, a video advertisement for BrickHouse Security was played for the court by co-defence counsel Steven Lack.

It purported to show how popular the company's wide-range of hidden surveillance equipment was and why it was "the best choice when buying a hidden camera".

Keating pleaded not guilty last March and two days later resigned from his post in the New Zealand Defence Force, ending a more than 40-year career.

The military leader also served as New Zealand's naval attache and senior technical officer for the navy to the US from July 2003 until December 2006.

The trial, which began on Monday, is expected to last two weeks.