One Betty Nichols is too many, but the department’s problem seems to have been shockingly widespread. An internal audit report, released last week, outlines numerous examples of flawed procedures and lost evidence. A preliminary search of the department’s database turned up 242 unsolved homicide cases with possible damaged or lost evidence since 1976. The report also describes sickening conditions at the city’s evidence warehouse, where temperatures soared above 100 degrees, a leaky roof damaged storage shelving and mice “and other vermin” destroyed and contaminated evidence packaging. At worst the report highlights horrifying incompetence among one of our most trusted public services. But the department insists the numbers are due partly to a faulty computer system, illustrating how even murder cases can slip through the cracks of underfunded departments. The chief has launched an investigation and plans to update the software.