Popehat On The Police Misconduct And The Presumption That Police Officers Are Telling The Truth
Ken White writes at Popehat about a cop, Armando Saldate, Jr., who was judged to be a liar on four occasions and a lawbreaker on five others -- information that was withheld from in trial of Debra Milke:

The State of Arizona, based on almost nothing but Saldate's word, has been trying to kill Debra Jean Milke for nearly a quarter-century. Today the United States Court of Appeals for the Ninth Circuit said they can't.

Two men murdered Debra Milke's four-year-old son, Christopher. Armando Saldate, Jr. claimed that she confessed involvement in the crime to him. He claimed that she did so in a private interrogation he conducted without recording it -- though he had been specifically instructed to record it. There was no physical evidence against Milke. The two men who killed her son did not implicate her -- in fact, they denied she was involved. The case against her rested on Saldate's word. The prosecutors -- the State of Arizona -- accepted Saldate's word uncritically.

...Multiple courts had found that Armando Saldate, Jr. had committed misconduct violating the rights of defendants ... [and] had lied repeatedly under oath ...

Yes, these facts might have led jurors to doubt the word of Armando Saldate, Jr. The State of Arizona -- through its prosecutors -- eliminated that dangerous possibility by withholding Saldate's record from the defense in the prosecution of Debra Milke. As Judge Kozinski said in today's Ninth Circuit opinion:

This history includes a five-day suspension for taking "liberties" with a female motorist and then lying about it to his supervisors; four court cases where judges tossed out confessions or indictments because Saldate lied under oath; and four cases where judges suppressed confessions or vacated convictions because Saldate had violated the Fifth Amendment or the Fourth Amendment in the course of interrogations. And it is far from clear that this reflects a full account of Saldate's misconduct as a police officer. See pp. 24-25 infra. All of this information should have been disclosed to Milke and the jury, but the state remained unconstitutionally silent.

The Ninth Circuit's opinion overturning her conviction is here.