Thanks to FP Blog mailing, which has picked up on a CNN report:
Pakistan arrested two senior police officials Wednesday in connection with the assassination of former Prime Minister Benazir Bhutto..... Aziz was the police chief in the Rawalpindi district at the time of Bhutto's assassination while Shehzad was the head of her security team.

The two have been accused of security breaches, covering up evidence by hosing down the crime scene and failing to conduct a post-mortem examination on Bhutto.
Link:http://edition.cnn.com/2010/WORLD/as..._igoogle_world