robert mcmahon

WBFO News file photo

The investigator who reconstructed the scene where 18-year-old Alexandria Rice was struck and killed stepped down Tuesday afternoon after spending two days on the stand.

Pool photo provided by The Buffalo News

In Erie County Court Monday morning, prosecutors began by laying the groundwork for Amherst Police Senior Accident Investigator Robert McMahon to testify in the trial of Dr. James Corasanti. 

Corasanti is accused of vehicular manslaughter in the July 8, 2011 hit-and-run death of 18-year-old Alexandria Rice.