Boasting he was working for Israeli intelligence? Sounds a lot like what Jonathan Pollard--except he is still alive. It's okay for Israel to threaten someone who may have passed on information to a non-enemy state, apparently, but it is consider cruel and barbarous for the US to do so when the evidence is overwhelming and unquestionable.
Second rocket fired from Gaza explodes inside Strip (Haaretz)
from the article: Source: Israel offered Zygier's family millions in compensation