According to the Independent, the IS militants had offered prisoner exchange deal in a letter to the family of James Foley, said the militant group.
The Islamic extremists claimed that despite their offer, the U.S. had not been interested in the prisoner exchange deal.
Aafia Siddiqui aged 42 is a trained neuroscientist from Massachusetts Institute of Technology who was arrested in Afghanistan in 2008.
Siddiqui was allegedly carrying toxic substances and papers that had references to constructing a bomb and a list of cities in New York.
She was convicted of attempting to kill U.S. military personnel and was sentenced to 86 years in prison.