Houston Police Dept: Biggest fuck-ups of them all?

Innocent until proven guilty, right? Well what if evidence was "lost" or "misplaced" that could lead to your ultimate acquittal? Apparently, the HPD has been under fire since 2002 for "misplacing" and "losing" evidence. I must be totally naive because I thought that an evidence room or analysis room - whatever - was like a vault. This doesn't seem to be the case with the Houston PD. They have compromised countless cases (some capital murder) because of this severe "misplacing" and "losing" of evidence. It was actually too late for one defendant as he's already been executed. The HPD has released two of God knows how many for faulty testing. Two. There are three cases in which the defense lawyers are planning on reviewing the "new" evidence.