Any nation that defies international law should face penalties, this includes Israel. International law was established to keep the peace and keep things far between the nations of the world and to protect the rights of its citizens. Defiance of that law in any way, shape, or form should garner penalties at the highest levels. No country is exempt.
If a law is defied, there should be consequences, whether we are talking about speeding, armed occupation of federal property or nations flaunting international laws. If a law is agreed upon by a consensus or convention of some kind, and a particular nation elects to defy that law, there must be harsh consequences. Without, the result will be international chaos and eventually global war.
If Israel is bound by international law like all other countries, then the answer is, yes they should be held accountable. They should face the same penalties for defying international law, that any other country would. In particular, their refusal to return the bodies of victims to their families, which is required according to International human rights laws.
It will become apparent from the following description of the actions taken by Israel since 1967 that Israel no longer considers the occupation of Palestine as temporary. This has become clear not only from the increasing number of voices within the Israeli governmental polity who advocate the outright annexation of the West Bank but also from Israel’s actions themselves, such as the construction of settlements protected by a separation barrier and connected to Israel via reserved roads, the appropriation of Palestinian land, of natural resources (including water), and the destruction of Palestinian villages. And with respect to East Jerusalem and the Golan Heights, Israel has already crossed the line and officially annexed these areas.