Prince Friso of the Netherlands died Monday, 18 months after he was buried in an avalanche and fell into a coma from which he never awoke, the royal house said. He was 44, according to dpa. King Willem-Alexander announced "with deep regret" that his younger brother Friso died from complications related to the severe brain damage he suffered in February 2012, when he was struck by an avalanche while skiing off-piste in the Austrian ski resort of Lech. The father of two had at first been treated at a London clinic but was transferred to palace of his mother, former queen Beatrix, in The Hague. Friso had only showed signs of "minimal consciousness" during his year and a half in coma, the royal statement said. The King and Queen Maxima are on their way back to the Netherlands after cutting short their holiday in Greece. Premier Mark Rutte said Friso's death was "incredibly sad," while thousands of citizens expressed their condolences online. Friso was the second son of Beatrix, who handed over the reign in April. He had renounced his place in the royal line of succession after it became known in 2003 that his fiancee and later wife, Mabel Wisse Smit, earlier had a relationship with a major drug dealer. Friso leaves behind his daughters Luana, 8, and Zaria, 7. He studied engineering, aerospace technology and business and had worked in the banking and technology sectors. Until his accident he was finance chief of the European uranium enrichment consortium URENCO in London. The prince was skiing with a local friend in Lech on February 17, 2012, when the accident occurred. He was buried under 40 centimetres of snow for at least 15 minutes. Friso's death was met with dismay in the luxury Alps resort, where the Dutch royal family has been staying for decades for their winter vacations. "As one of many people in Lech who knew the prince from childhood, I am personally deeply shocked and moved," Mayor Ludwig Muxel told Austrian press agency APA.