Not all heroes walk on two legs.
He's kept Marietta, its officers and the community safe since 2007.
Thursday night was Diego's last shift.
Police K9's are trained for years and continue training their whole life to assist officers in the line of duty.
It's not a small venture.
Diego is now 9-years-old.
The decision was made because of this health.
He served on hundreds of calls, biting only those he had to.
His handler, Officer Glen McClelland, says when he's getting ready for work, Diego goes and sits by his boots until he's ready.
When he's on duty you can't even tell he's getting older.
But Officer McClelland says he wants Diego to have a good life after retirement, so now was the time.