A former member of Saddam Hussein’s intelligence service was arrested in the assassination of Ali Faisal al-Lami,  a Shiite, politician who oversaw efforts to purge scores of candidates from national ballots because of ties to the former government, the Iraqi police announced Tuesday.
 

They said the suspect was arrested in the Taji area north of Baghdad but did not release his name or provide any evidence tying him to the killing. Mr. Lami, a Shiite Muslim, was gunned down Thursday night as he drove through Baghdad, becoming one of the most prominent victims of an assassination campaign aimed at security forces and government officials. As the head of Iraq’s Accountability and Justice Commission, Mr. Lami played a central role in last year’s politically divisive attempt to bar a number of candidates, many of them Sunnis, from parliamentary elections.