This story started here.
On reading this report, my employer noted that I didn't mention Foster's motive. To tell the truth, we didn't investigate this at the time. I think we were just glad the case was over, and we were both uncomfortable with how it had been resolved, but of course there was a trial and it all came out there.
Ron had wanted to know from the first night, and she had been rather miffed that we didn't have all the answers at out fingertips. Not that she cared why Foster had committed the crime, but she did seem to think that solving a crime without knowing the motive was sloppy workmanship.
We did do a thorough investigation before the trial, and it became clear almost immediately that there had been a disagreement between Foster and Barney about a drug deal they had been working on together. This led us into a whole different and much more complex investigation, which I will chronicle in its own right at some point.
Barney had wanted to sell the drugs to their friends in U-town. His main concerns had been breaking even and having a good time. Foster had needed cash, however, and had wanted to sell the drugs over in the city, where there was much more profit to be made, but also the chance of arrest.
However, as I said, that's another story.