The rule allows officers suspected of wrongdoing to wait two days before answering questions from superiors.

The case, people who worked on it say, centered on a group of officers suspected of robbing drug dealers.

Rather than report them, they too would seek to transfer officers suspected of corruption to other precincts.

There are still officers suspected of drug links in high Defense Forces posts.

But the two officers suspected of the killing are white, longtime members of department with reputations for toughness.

In one meeting, he wrote afterward in a cable, he confronted the defense minister about specific officers suspected of abuse.

The final group includes officers suspected of having engaged in improper conduct but for whom evidence is incomplete.

An American officer suspected of having prior knowledge of the killings was also questioned.

And "officers strongly suspected of trafficking in narcotics rarely face criminal prosecution," according to a recent State Department report.

Two white officers suspected of killing him were suspended without pay, as were five officers who witnessed the beating.