fewer than one in five massachusetts residents want boston marathon bomber dzhokhar tsarnaev to be executed believing a quick death .
last week prosecutors described the 21-year-old as ` america 's worst nightmare ' insisting he deserves to die for carrying out one of the bloodiest attacks on us soil since 9/11 .
fewer than one in five massachusetts residents questioned believed he should be put to death with 63 per cent in favour of a life sentence .