taken a big hit and the person they say is responsible was one of their own. a crime lab chemist is being investigated for allegedly switching with over the counter meds. >> more than 2,000 criminal cases at risk of being thrown out or overturned. a pensacola, florida chemist accused of swapping out drug lab evidence with over the counter aspirin. >> it could be personal use, trafficking, each of those. we don't know. >> this is significant. the florida department of law enforcement spokesman told cnn, we've never had to undertake something like this before. the investigation spans 35 counties across the state of florida. in all, 2600 cases over the past eight years. all of them potentially impacted because of alleged evidence tampering. >> our first priority is to find out what couldly what happened in this case and work with the