Police power to seize the personal property of citizens is the exercise of authority that should never be taken lightly or capriciously. Citizens are ordinarily under no obligation to prove ownership of any property found in their possession. Conversely, the burden is upon the officer to prove that property is not legally in possession of a citizen. Unless investigation can establish otherwise, it should be presumed that property found in the possession of any citizen is that citizen's property and, if such property is seized for any reason, the citizen is entitled to recover that property when there is no longer a bona fide reason for the department to retain it. (This policy includes weapons; it excludes any contraband.) It is, therefore, the policy of this department to seize and impound property only when a legitimate need so requires and to retain such property only so long as that need is served.