He's a 30-year veteran of the police force who has spent more than a decade handling evidence in Metro's crime lab.
But Metro police officer Michael Pyburn abruptly resigned after police say he falsified records to cover up a faulty ballistics report.
NewsChannel 5 Investigates has learned Metro took the dramatic step of shutting down its ballistics testing after finding the problems didn't end with Pyburn.
"The administration of the police department is very, very concerned and displeased by what has happened," says Metro police spokesman Don Aaron.
Metro placed a letter in Pyburn's personnel file this week, stating: "Officer Pyburn was routinely ignoring the standards and procedures put in place to insure quality control."
It goes on to state, "Officer Pyburn would have faced significant disciplinary action up to and including termination had he not retired."
Metro police have also reassigned the other two officers in the ballistics lab after finding other problems such as officers not cleaning bullets before testing.
"We are going to start anew personnel wise and there will be checks and balance put in place," says Aaron.
But the implications are enormous, and attorney David Raybin says the problems at the ballistics lab could call into question past convictions.
"You might have a dozen or more serious murder cases or armed robbery cases that have to be re-tried because of that its really sad," says Raybin.
Currently, the Tennessee Bureau of Investigation is going back and re-testing the ballistics on all pending criminal cases. And the Davidson county district attorney's office is reviewing past convictions going back as far as 2004.
"We are not aware of any criminal cases that have hinged on ballistic evidence," says Aaron.
This whole thing started when Officer Pyburn determined five bullets came from the same gun, but a TBI test revealed only three did had come from a single gun. That meant 2 guns were used instead of one.
That's when police say Pyburn tried to cover-up his mistake by amending his reports.
Metro says it is determined to re-open its lab. The police department spokesman says the department realizes this situation will hurt people's confidence in their ballistics testing.
"It's understandable we don't have that confidence right now and our law enforcement partners don't either," says Aaron. "That confidence will be restored. We're determined to restore that confidence but its going to take a few months."