DOC,
There is NO evidence that the apostles were martyred.
Why, oh why, do you keep claiming that there is?
Where's your evidence?
Thank you....
Well James, the brother {some say cousin} of Jesus was not an official apostle, but being the first bishop of Jerusalem, he comes close.
Here is what historian Josephus says about him:
Festus was now dead, and Albinus was but upon the road; so he assembled the sanhedrin of judges, and brought before them the brother of Jesus, who was called Christ, whose name was James, and some others, [or, some of his companions]; and when he had formed an accusation against them as breakers of the law, he delivered them to be stoned:...
Josephus on the Death of James brother of Jesus, in 62 C.E. Josephus, Antiquities Book 20: chapter 9.
http://religiousstudies.uncc.edu/people/jtabor/james.html
And we know gospel writer Luke (who was praised by Sir William M. Ramsay as a great historian regarding things that can be proven by historical and archaeological evidence) stated Stephen was stoned for his Christian faith and the apostle Paul witnessed this stoning.
Regarding the actual apostles martyrdom there is historical evidence, this site on Wiki just didn't spring up out of thin air.
http://en.wikipedia.org/wiki/List_of_Christian_martyrs
The early church fathers wrote on many of these martyrdoms. Their writings are historical evidence. How much weight you want to give those writings is subjective.
And we know that the main apostle Peter was preaching in Rome at the end of his life.
http://www.internationalskeptics.com/forums/showthread.php?t=85633
Just the very act of being in Rome preaching and most likely leading the church there is evidence that Peter was certainly willing to die for his faith (given what we know about emperor Nero and his terrible tortures and killing of Christians in 64AD).