Mysterious DNA Contamination

This story is curious.

From AZCentral.com:

Evidence from criminal cases in Arizona and Florida, including a rape, a murder, and an assault, has been contaminated with the DNA of an unknown female who has no connection to either the suspects or the crimes.

The unknown DNA has been detected in at least three cases in Tucson and an undisclosed number of cases in Florida, leaving authorities pointing to possible contamination from a supplier of testing materials to crime labs.

Prosecutors and police say the presence of unknown DNA does not hinder their ability to prosecute suspects or negate other evidence in the affected cases.

Unknown female? Florida and Arizona? Prosecutors and police don't think it's a problem?

Something is wrong here.