A device thrown at the west Belfast home of the brother of murdered solicitor Pat Finucane was a "crude explosive device that did not ignite".
The attack happened at Martin Finucane's Glenties Drive home around half 6 this morning.
A window was smashed and a vehicle was heard making off from the scene.
Two people in the house were unharmed.
Martin Finucane (pictured far right) has been left shaken by the ordeal.
"My message to them is to stop, to cease, and I hope that I am the last," he said.
"But explain to me why you targetted me, and the reasons for it, because there's no justification for it -- there's no moral justification for it whatsoever."