What is the test for establishing a constitutional violation by destroying or destroying evidence?

In order to establish a constitutional violation, the defendant must demonstrate that the government acted in bad faith in failing to preserve the potentially useful information. Arizona v. Youngblood, 488 U.S. 51, 58 (1988). Bad faith can be demonstrated where there is evidence in the record of "official animus towards [a defendant] or of a conscious effort to suppress exculpatory evidence." Trombetta, 467 at 488. "The presence or absence of bad faith turns on the government's knowledge of the apparent exculpatory value of the evidence at the time it was lost or destroyed." United States v. Cooper, 983 F.2d 928, 931 (9th Cir. 1993) (citing Youngblood, 488 U.S. at 56-57).