the family of an american hostage killed in a us drone strike gave his al qaeda captors money in a failed bid to guarantee his release .
it has also been claimed dr warren weinstein , from rockville , maryland , and a fellow aid worker were used as a shield to protect a senior al qaeda operative while in captivity .
the 73-year-old was killed alongside giovanni lo porto during an anti-terrorist strike on the afghanistan-pakistan border intended to kill members of the group .