A home heating oil distributor and his son who scammed customers - including an old people's home - out of £100,000, have been sent to jail.
Robert White, 56, of Creightons Green Road, Holywood, was sentenced to 15 months in prison.
His son, Paul, 36, of the same address, was told he would spend six months in jail.
A judge at Downpatrick Crown Court told the pair that they were guilty of a "serious breach of trust".
An earlier court hearing was told that the oil fraud racket came to light in late 2013, after Barr Hall residential home, Portaferry, became concerned about the amount of heating oil it was burning and contacted police.
The court heard that on 20 December that year, there were 900 litres in the 2,500 litre-capacity tank.
A delivery of 2,000 litres had been ordered for the next day. When police dipped the tank following the delivery of oil from D White and Sons, there was just 2,400 litres in it.
In follow-up searches at the firm's office and the defendants' homes, police seized more than £20,000 in cash along with diaries, delivery dockets and invoices.
They believed that delivery figures and invoices did not tally. A diary contained figures that officers believed was the amount of oil they were skimming off deliveries.
In court on Monday, the judge said the men's crimes were "clearly planned and premeditated''.
He said Robert White was the "main instigator'' in the fraud whereby 50 litres of a 500-litre delivery and 100 litres of a 1,000 litre delivery were "stolen from customers over a five-year period, put back on the truck and recycled to other customers giving you 100% profit''.
The pair admitted fraud by false representation and acquiring criminal property - the money they made from the oil fraud.
The judge said this was an "easy crime to carry out but a difficult one to detect".
"It was only by sheer good fortune that some of the customers had detected that they were not receiving the full amount of oil and the matter was reported to the police,'' he said.
He told Paul White that he had a "lesser role" in the fraud, but had "actively participated" in it.
Paul White's mother, Wendy, 56, from the same address had earlier pleaded guilty to a single charge that she knowingly entered into an arrangement concerning criminal property.
The judge told her she was being spared prison by "the skin of your teeth". A community service order of 150 hours was imposed.
The judge said police found "significant quantities of cash" at the family home as a result of the fraud.
He said Robert White would spend seven and a half months in custody and the rest on licence. His son, Paul, would spend six months in prison and six more on licence.
The judge said that the family home was now up for sale. He adjourned confiscation proceedings so that the £100,000 defrauded from customers could be recovered.