Surviving Boston bombing suspect is awake and responding to questions in writing

The surviving Boston bombing suspect is awake and responding to questions in writing according to several US media outlets.

Dzokhar Tsarnaev is being treated in hospital for serious wounds sustained during a manhunt. He is the main suspect behind Monday's twin bombings that killed three people and wounded 180 others at the Boston Marathon.

He suffered a throat injury that keeps him from talking but is reported to be responding 'sporadically' in writing. His older brother Tamerlan who was killed in a shootout with police is also a suspect.

The boys father Anzor has told a Russian newspaper his sons are innocent.

Meanwhile a police officer injured while trying to capture the suspects is still in a serious condition.

Richard Donohue's brother Edward has spoken out.

"I want to thank everyone who has assisted our family in this ordeal - to our enemies: we will persevere and we will fight, because we know no other way to live but free" he said.