Mohamed Sawalha had been identified by the BBC in 2006 as a senior Hamas activist.
Palestinian guards opened the door of the main prison in Gaza, freeing scores of criminals and Hamas activists.
The Israeli military would confirm only that it had detained five Hamas activists in the West Bank overnight.
The army said one of the men was a Hamas activist suspected of planning terror attacks.
Twenty more lower-level Hamas activists will be freed from prison soon and permitted to remain in Jordan, officials in Amman said.
This event precipitated Israel's decision to deport 415 Hamas activists to the Lebanon four days later.
In an exchange of fire, three Hamas activists were killed, including a cousin of Mr. Houl, who was not at home at the time.
More than 200 Hamas activists have been detained since an Israeli army crackdown in May.
Which it did last fall, expelling several key Hamas activists from the country and shutting down Hamas offices in Jordan.
At the time of his death, journalist Robert Fisk calls Akel "the most important Hamas activist ever shot dead by the Israeli army."