Questions look set to be asked after two Russian oligarchs, both linked to gas giants, apparently murdered their wives and daughters before killing themselves - within two days of each other, writes Newsweek.

“In both cases, the alarm was raised by the slain families’ surviving child.

Former Kremlin official and Gazprombank vice-president Vladislav Avayev, 51, was found dead in his luxury Moscow apartment alongside the bodies of his wife and 13-year-old daughter on Monday. It appeared he had shot them before turning the gun on himself. The bodies were found by distraught 26-year-old daughter Anastasia after she was unable to get hold of her family.

The following day former Novatek deputy chairman Sergey Protosenya, 55, his wife Natalya, 53, and 18-year-old daughter, Maria, were found dead at their Spanish mansion. The scene suggested the women had been stabbed, before Protosenya hanged himself in the garden. The alarm was raised by the couple"s teenage son, who was staying in France, after he was unable to reach his parents at their home in the coastal town of Lloret de Mar.

Spanish investigators are now reportedly trying to work out whether the Protosenya deaths were the result of a domestic murder-suicide or an organized hit”, - writes the author.