The Knoxville Police Department is in mourning following the death of one of its former four-legged officers, K9 Gunner. The retired police dog passed away at the age of 13, as confirmed on Wednesday by a department social media post. “We are saddened by the death of retired KPD K-9 Gunner, who passed away this morning at the age of 13,” read the announcement on Knoxville Police TN.