dr warren weinstein died during the counterterrorism operation in january .
the 73-year-old was captured from his home in lahore , pakistan , in 2011 .
his family are said to have transferred money to his kidnappers in 2012 .
they asked for the release of prominent afghan prisoners in return .
the transaction did not lead to his release and his family have since slammed the us government for their ` disappointing ' reaction .
us officials insist the family will be receiving compensation for his death .