Israel's defence minister has said his country is watching to see whether the Palestinian Authority prosecutes men suspected of killing two settlers.
Mr Barak's warning follows Israeli demands for action against gunmen
Ehud Barak said Israel would track the suspects down if they were released.
Palestinian officials have said the men will be tried and face jail sentences if they are convicted.
They are suspected of shooting the Israelis, both off-duty soldiers, in an ambush near Hebron in the occupied West Bank on Friday.
Israel has often accused the Palestinian government of not doing enough to tackle militants.
Israel says the men were members of the Palestinian Authority President Mahmoud Abbas' Fatah party, and that one was a member of the security forces.
"These people need to rot in jail until their last days," Mr Barak told Israel Radio.
"We will see if the Palestinian Authority is opening a revolving door for them and if so, the Israeli Defence Forces and security services will know how to put our hands on them."
Friday's attack renewed demands in Israel that the Palestinian Authority cracks down on militants. Israel has made progress towards any peace deal conditional on such a crackdown.
Hebron is the scene of frequent violence between Palestinians and settlers.
Hebron is the only place in the West Bank where a small community of Jewish settlers lives in the heart of a Palestinian city.
Under an agreement with the Palestinian Authority, Israel pulled out of 80% of Hebron in 1997, remaining in an area around the old city where 650 Jewish settlers live among about 30,000 Palestinians.
All Israeli settlements built on land captured in the 1967 war are considered illegal under international law, although Israel disputes this.