Officer Warnecke was shot and killed by two robbery suspects outside of a grocery store at 4312 North Grand Boulevard. Two men just robbed the store of $1,000 and were fleeing when Officer Warnecke pulled up to the store, not knowing a robbery had just been committed, to do a business check. As he was getting out of his patrol car the store manager pointed to the suspects hurrying across an icy parking lot and Officer Warnecke called out to them. One of the men approached Officer Warnecke and second man circled around and shot him in the back three times. Before fleeing, the suspects stole Officer Warnecke's watch, wallet, and revolver. Both men were apprehended a short time later.

Officer Warnecke was a WWII US Navy veteran and served with the department for 27 years. He was survived by his wife and two children.