After the all the analysis the NYT reports:
...in the end, it apparently came down to a bitter local grudge. A former justice of the peace whose legal and political career collapsed in a hard-fought legal battle was accused Wednesday of killing the two prosecutors, who had been his courtroom rivals. And his wife not only named him as the gunman, but also confessed to having been the driver in both shootings as part of her role in the vendetta, the authorities said.
Link:http://www.nytimes.com/2013/04/18/us...pagewanted=all