So say a slave owner enters a state where slavery is outlawed and that slave is discovered. Can the state take away the slave as they are considered property? Would they become free or be owned by that state. How would this process go? and is there any example of this?
The term "contraband" specifically refers to "contraband of war," the legal justification used by General Benjamin Butler to refuse to return slaves to bondage. Therefore, the direct answer to your main question is no.
Supreme Court decisions such as Dred Scott v. Sandford and laws such as the Fugitive Slave Act eliminated the possibility that a slave could be freed solely by entering a free state.