Sure. Here is the link to that department s Website:http://www.police.co.nassau.ny.us/index.��This site will give you more information than you need, but it is all interesting and worthwhile.1. I would think the Commissioner (named on the site) is the top official. Go to the site, click on Commissioner in the left menu.2. Until you have established a more casual relationship, it is definitely best to refer to the commissioner and other officials with their title. Dear Commissioner (Last Name Here) would do just fine. Likewise, Dear Sergeant, Lieutenant, Captain, Officer, etc would be appropriate. If there is any doubt about the exact rank or title, you may certainly use Mr., Mrs., or Ms, depending on the individual case.3. The ranks are also given on the site. The menu at the left is just full of good stuff.4. I added this one. Please, please, please, when you write to them spell their name correctly. This is not only for the individuals but also for the department. Notice that you have spelled the county as Nassua twice, but it is actually Nassau. Well, good luck on your project. It should be a good one for you.
1. Lawrence W. Mulvey 2. Dear Commissioner Mulvey:3. Commissioner of PoliceAlso, you should be careful to spell Nassau (a before the u, not after) correctly in your letter.