Washington- In an email to the family members of slain American journalist James Foley, his captors from the Islamic State militant group demanded release of several prisoners, including the Pakistani woman scientist Dr Afia Siddiqi who has been convicted of terrorism charges in the US. In their email dated August 12, to family members of Foley, the Islamic State or ISIS, claimed that the US refused several offers of release of the journalist, which included not only money but also the exchange of prisoners. "You were given many chances to negotiate the release of your people via cash transactions as other governments have accepted. We have also offered prisoner exchanges to free the Muslims currently in your detention like our sister Dr Afia Siddiqqi, however you proved very quickly to us that this is not what you are interested in," said the email, which was released by The Global Post. "You have no motivation to deal with the Muslims except with the language of force, a language you were given in 'Arabic translation' when you attempted to occupy the land of Iraq!" said the email and added that Foley would be "executed". The Islamic State this week released a video showing one of its members beheading Foley, who was abducted in Syria in November 2012. Dr Siddiqui, an MIT-trained neuroscientist, was arrested in Afghanistan in 2008 and found to have documents on chemical weapons, dirty bombs and viruses indicating she was planning attacks against American enemies, reports said. Later, she was jailed by a US court for 86 years.