Lapse in concentration leads to dream opportunity for thieves

He could be any customer entering a suburban bottle shop. Instead he is a thief, who has stumbled across a perfect opportunity.

The family-owned liquor store in Bass Hill, in Sydney's south west, has just shut for the day, but they've forgotten to lock the door.

It starts with one bottle of liquor and a tray of cigarettes. Four hours later, the thieves are back, their faces covered by hoodies and after top-shelf liquor.

Owner Van Tran says the lapse in concentration was a costly mistake.

"One mistake cost me nearly $20,000," he said.

It's a valuable lesson for his eight-year-old Steven.

Mr Tran lost his wife to cancer two years ago, leaving him to raise their young son on his own. 

He says he runs his business around the clock and even still struggles to make money.

This father and son are hoping forensic police will uncover a clue which will lead them to these robbers.

"How would you like it if people did that to you?" Steven said.