Mark Andrew Sandery, 41, has pleaded not guilty in the South Australian District Court to possessing an SKS semi-automatic rifle without a licence on December 20, 2011 at Semaphore and to possessing a gun while a firearm prohibition order was in place.
Judge Sydney Tilmouth, who is hearing the trial without a jury, has been told Sandery's young son was shot in a home invasion at the Semaphore house on September 30, 2011.
The premises were searched by police on December 20, as was a nearby flat where Sandery sometimes stayed.
Prosecutor Brian Nitschke has alleged that, even though Sandery was not in Adelaide when the gun was found, he was the occupier of the house or it was under "his care, control or management".
But his lawyer, Andrew Moffa, said Sandery knew nothing about the gun and had arranged for tradesmen to repair the house so it could be handed over to the real estate agent.
On Thursday, the judge was played a number of intercepted calls.
On December 20, Sandery was phoned by a female who said police were raiding the Semaphore flat and wanted to search the house.
A male then rings him about the raid, leading Sandery to say, "I am f...ed".
Mr Nitschke has alleged this indicated a fear of what might be located at the house.
Under cross-examination from Mr Moffa, Detective Sergeant Mark Heading told the judge that steroids and a white powder were found in the flat.
The trial is continuing.