Reporting for duty
1. I would write the story. while the police officer has made a considerable threat in refusing to speak to the journalist in question, his threat would only add to the severity and impact of the story. This story is in the public interest, and therefore it represents a large proportion of the key news values. In addition to this the chief-of-staff would like you to write the article therefore if you don't someone else would, and the police officer would not speak to you anyway, therefore there is little consequence in writing the article.
2. I would look into the agencies available to help this woman. all threats of suicide must be taken seriously. in addition to this i would still report the story but not use names, and be careful of the descriptions i used.
3. I would report the story. Many of these DUI stories have been reported in recent times, and have not ruined a career. In addition to this there are benefits to reporting the story for example scooping competition newspapers. as you have had contact with the celebrity it may be plausible to get a quote that will balance the article.
4. i would conduct an investigation into the jurors, but would not make any direct allegations. i may write a small article that states allegations have been made, but would not directly state specific details about any of the jurors.