Rabbinic scholars have long argued whether Judaism obligates a Jew to die as a martyr for the faith, or whether a Jew can pretend not to be Jewish so as to avoid such a fate. Unfortunately, this issue which has been relevant so often in Jewish history, was very significant just a half-century ago, during the Holocaust, when many Jews struggled with the issue of whether it was permissible for them to pretend to be non-Jews, so as to save their lives. Many Jews who had the opportunity to do so did so and survived. Others held that it was wrong to pretend to a non-Jewish identity, and that one should die as a martyr. The Nazis were only too happy to grant their wish.
In Pearl's case, it is likely that even had he wanted to, he could not have denied his Jewishness. His name is a characteristically Jewish one, and his murderers (whose intentions towards the Jews are of course similar to those of the Nazis) had clearly targeted him for kidnapping in large part for that reason. But whether he had a choice or not, the fact that he was murdered because he was a Jew, and that his final words were a statement of his Jewishness, means that he enters that unhappy, very long, list of Jews who have died al kiddush hashem. For whatever the consolation is worth to his family (and I hope it does help console them), Jewish tradition believes that Mr. Pearl's soul now sojourns in a very high place, one reserved for martyrs and holy people.
As for those who murdered Daniel Pearl, my broken heart thinks of the words of a 1,000 year-old Jewish prayer, composed in honor of Jews who were martyred during the Crusades: "May God avenge his blood" (because the prayer was written in commemoration of thousands of martyrs, it says "their blood" instead of "his blood").