Writing a letter in a professional setting is very different than writing to your grandma. As you might expect, it requires a certain level of formality. You may write a letter to a prosecutor (a lawyer who builds a case against a defendant in court) if you have information about a particular court case or want to file a complaint about how a case was handled.
TL;DR (Too Long; Didn't Read)
A letter to a prosecutor should follow the format and etiquette of a business letter. It is not necessary to type the letter, but if it is handwritten, make sure it is legible. Try to limit the letter to one page.
Business Letter Format
You can format a letter to a prosecutor as a block, modified block or semi-block. It does not matter which format you choose, as long as you stick to the same format throughout your letter. Block letters are left-justified and single-spaced with double spacing between each paragraph. Modified-block letters have the sender's and recipient's addresses left-justified and single-spaced and the date and closing tabbed to the center. Semi-block letters are the same as modified block letters except each paragraph is indented, not left-justified.
Business Letter Etiquette
Your letter to a prosecutor should include certain sections. If your address is not included in a letterhead, add it at the top left of the letter. Include only your street address, city and ZIP code. One line below your address, write the date on which you wrote the letter. Use the United States date format, which places the month before the day, for example, "March 14, 2018." Leave two spaces under the date and write the name and office address of the prosecutor. The address should include the prosecutor's organization, street address, city, state and ZIP code, one under the other.
Begin your letter with a suitable greeting. To address a prosecutor, use "Dear Mr." or "Dear Ms." followed by the prosecutor's last name. (If you know a female prosecutor favors "Miss" or "Mrs." use her preference.) The next section summarizes the topic of the letter and begins with "Re:", for example, if you are writing about a case in which the defendant is called Jones, you might write "Re: Jones case." The main body of your letter comes next, which explains the purpose of your letter. Try to limit the main body of your letter to two or three concise paragraphs.
Finally, the closing should be "Sincerely," followed by your signature. Beneath your name, write your full name, street address, city, state and ZIP code.