1 Exhibit 99(a) EXHIBIT A - LETTER FROM ARTHUR ANDERSEN LLP STATING AGREEMENT WITH DISCLOSURE June 23, 1998 Office of the Chief Accountant Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 Dear Sir/Madam: We have read Item 4 included in the Form 8-K dated June 24, 1998 of Horizon Bancorp to be filed with the Securities and Exchange Commission and are in agreement with the statements contained therein. Very truly yours, Arthur Andersen LLP cc: Mr. Thomas McCormick, President, Horizon Bancorp