The Public Prosecution launched on Tuesday a probe into an explosion that targeted a hotel in Arish city early in the day.
A booby-trapped vehicle exploded outside the Swiss Inn hotel in Arish, where judges overseeing the parliamentary vote were staying.
Sappers and criminal experts were assigned to inspect the explosion site.
Prosecutors ordered a DNA test to identify the bodies that were found at the site of the blast.
The attack left two judges and three policemen dead.