A former policeman who shot dead his common-law wife with his service pistol after an argument, was sentenced to 20 years' imprisonment by the High Court in Pretoria on Friday.
Former crime prevention policeman Godfrey Boitumelo Modikoe (34) murdered Tshepiso Mafatle in December 2010.
Judge George Webster said this type of crime appeared to be on the increase.
He said police officers were the guardians of society, and their firearms were intended to be used for protection in a threatening situation and not to shoot their spouses.
Mafatle died at Modikoe's family home in Klipfontein, outside Pretoria, after being shot once in the face.
She and the couple's two children had lived with Modikoe's mother after he moved out because of their volatile relationship.
Modikoe pleaded guilty to the murder and apologised to Mafatle's family for the loss and suffering he had caused.
He claimed he had not intended killing Mafatle, and had acted on the spur of the moment in a fit of anger because Mafatle was swearing at him.
Modikoe admitted deliberately contravening a protection order which forbade him from visiting the house.
Former colleagues described Modikoe as a good worker, but said there had been reports about him physically abusing his wife and refusing to maintain his children - which had required the intervention of his captain.
Modikoe said in an explanation of plea that he had battled depression for years, and had been diagnosed with an undisclosed illness, but he did not present evidence to prove his claims.
Webster said it was clear Modikoe had been in control of his faculties on the day of the shooting.
He said Mafatle had done nothing to provoke such a violent reaction.
Modikoe had been forbidden from visiting his mother's house, and the decision to visit his children that day had been deliberately provocative, especially given his history of being a poor provider.
He was on duty and was armed with his service pistol on the day.
Webster said that when there was a reaction to his failure to buy clothes for his children, he ought to have done the most sensible thing, which was to turn around and walk away to avoid confrontation.
Instead, he shot Mafatle in the face and walked away.
Counsel for Modikoe asked for a sentence of less than 15 years' imprisonment, but Webster said this would not fit the crime or the accused and would detract from the interests of society.
The court earlier heard that Mafatle's family had not forgiven Modikoe and was still angry with him because he had not sent a senior member of his family to apologise for his conduct.