It's a suspense thriller type story, and in it, a woman is avoiding be subpoenaed to testify in a felony court case, but she does not want to get involved. So the prosecutor has her arrested with a material witness warrant to secure her testimony. After spending a few hours in custody, the prosecutor orders her to be released, since he thinks he made his point, and wants to be able go home to her own bed for the night, since her testimony date is next the day. The investigating cop on the case offers, to give her a ride back home. Other villains who are accomplices of the defendant, but unbeknownst to the police, are waiting her, for when she comes home. I wrote it so that the cop gives her a ride, cause I wanted the cop to get caught in the crossfire between her and the villains in the process. However, my plot dilemma, is that I have no explanation as to how the villains new she was subpoenaed to testify, no more than one day later. How could they have found out that she was not only arrested on a material witness warrant and subpoenaed, but released the same day as well, so they could wait for her at her place, only hours later? There are several fiction books and movies though, where villains will show up by surprise, to make attempts on other characters lives. Should I just keep it a mystery to the reader like those, or is this something that has to be explained do you think?