If they have seized the property because they think that it is some way linked to the crime in question then yes, they can hold it until it is inspected.  They can not hold it hostage unless you talk to them.  You might want to speak with an attorney in your area on this matter and see if he or she can represent you for the purposes of the interrogation (for lack of a better word).  If you have nothing to hide then you should be fine but it is always better to have some one there to make sure that your rights are protected.  And speak with them about getting your property released.  Good luck to you.