Surviving suspect's injuries prevent him from communicating as FBI faces scrutiny over contact with Tamerlan Tsarnaev in 2011The surviving Boston bombings suspect is so seriously injured that investigators may struggle to interrogate him effectively, it was suggested on Sunday, as further questions were raised about the FBI's previous contacts with his dead brother.Dzhokhar Tsarnaev, the 19-year-old accused of planting the pressure-cooker bombs with his older brother Tamerlan, was being treated in hospital for a reported bullet wound to the throat and was unable to speak.