The murder victim's wife was blind.

World War II. During the attacks on Berlin in the winter of 1943-44, wave after wave of British bombers swept over northern Europe and dropped their lethal loads on the German capital. A fair percentage of the bombers would fail to return from these 'ops', and RAF planners calculated the life expectancy of the airmen in weeks rather than months.
Therefore it did not seem strange when a Lancaster named D-Daisy landed at its base in England after a bombing run, and a member of the crew was found dead.
However, one person soon came to the conclusion that this man had been murdered. And the person who discovered this happened to be blind since birth. Her name was Daisy and she was the victim's wife. She was very blonde and very pretty; also very young. That's why no one would listen to her.

So she had to find the killer on her own.