Natalie #27 is right on point. No-one knows who, or what, Israeli nationality (Jew, Arab, Druze) to which the killer belonged, or even why the crime was committed. But we all know that US co-oppression of the Palestinians in a militarily occupied area (which is where this tourist chose to go) carries natural high risks. This, and not specific evidence, is why the Israeli police consider one hypothesis of motive to be Palestinian resistance (in Hebrew, always spelled "terrorism").
Ya'alon okays administrative detention of Jewish extremist suspected in church arson (Haaretz)
from the article: Body of U.S. tourist found near Jerusalem; police suspect terror attack