A St. Paul police crime lab analyst testified Friday that she could not recall asking anyone to evaluate a testing instrument even though she thought it was interfering with test results.
Public defender Lauri Traub noted that according to maintenance logs, the machine in question wasn't serviced until several months after those tests had been conducted.
Traub and public defender Christine Funk are trying to raise enough doubt about the lab's evidence handling to stop the Minnesota Bureau of Criminal Apprehension (BCA) from retesting the same evidence. They believe that evidence could be so contaminated that no tests would be valid.
Criminalist Roberta DeCrans said that she conducted tests in May 2011 that experienced interference she attributed to "column bleed," which is when a polymer in the machine leaks and appears on a graph mimicking a substance.
The machine was serviced in January 2011, and wasn't serviced again until January 2012, Traub said. She asked DeCrans if the apparently faulty part, a tube that is coated with the polymer, should've been replaced.
"I guess that would be a possibility," DeCrans said.
"Why didn't you call maintenance when you saw that significant column bleed?" Traub asked.
DeCrans said she could not recall why she didn't act.