text: Heinrich Boere, who is in a wheelchair, was taken by ambulance from his nursing home in Germany to a prison hospital.
  He was sentenced in March 2010 after confessing to the killings.
  A German court rejected an appeal against his jail term and a medical expert said he was fit to serve his sentence at a "suitable" facility.
  During his trial, Boere had admitted to the killings in 1944, but said he had been acting on orders from his superiors.
  He shot dead Fritz Bicknese, a chemist and father of 12; Frans Kusters, a Dutch resistance member who owned a bicycle shop; and Teun de Groot, who helped Jews go into hiding.
  Boere argued that he risked being sent to a concentration camp if he refused to carry out the shootings.
  "At no time in 1944 did I act with the feeling that I was committing a crime," he told the court during his trial, but added that 65 years later he saw things from a different perspective.
  The presiding judge, Gerd Nohl, said all three killings had been carried out "on a totally random basis" and constituted murder.
  Boere was born in Germany to a Dutch father and a German mother but grew up in the Dutch town of Maastricht.
  He joined the Waffen SS when the Nazis overran his hometown in 1940.
  In 1947 he escaped from a prisoner of war camp in the Netherlands and returned to Germany.
  A tribunal in Amsterdam sentenced him to death for the killings in his absence in 1949, but this was later commuted to life in prison.
  He was never extradited and a German court ruled in the 1980s that the Dutch trial had been unfair because Boere had not been present.
  In April 2008, more than 60 years after the killings, he was indicted in Germany.
  After legal arguments about whether he was well enough to stand trial he was eventually convicted last year.
target: A 90-year-old man has begun a life sentence for shooting dead three Dutch civilians when he was a member of a Nazi SS hit squad during World War II.