Normally no-one would pursue you after the case has ended. If, however, the case was continued the police may take you into custody and hold you until you have testified. This sometimes happens and sometimes does not. A great deal depends on how you received the subpoena. You should consult with a local attorney and give him/her all of the details.
David C. Beyersdorf
I beg to differ with my colleague; you never have the right to ignore a subpoena. If you do you will be in contempt of court and could be either fined and/or jailed. It is true that if the case is dismissed your fauilure to appear may be ignored but why take the chance?