Complex sentence: According to Michael Burleigh, Michael Rubin and Mark Hibbs, the assassinations may have been carried out by the dissident Mujahedin-e-Khalq group on behalf of Mossad.
Split into simpler sentences: According to Michael Rubin and Mark Hibbs, the assassinations may have been carried out by Israel. It's also said that the dissident Mujahedin-e-Khalq group has done the killings on behalf of Mossad.