It's been exactly a year and a half since Oscar Grant was shot in the back while he lay face down on a train platform by former BART cop Johannes Mehserle. Today, Mehserle faces his last pre-trial hearing before his trial gets underway with jury selection this week. Mehserle's been charged with second-degree murder and has pleaded not guilty. Michael Rains, Mehserle's attorney, is expected to make the claim that Mehserle mistakenly pulled out his gun when he meant to reach for his Taser when he shot Grant on New Year's Day 2009. Rains wrote in a pre-trial motion: "So, the relevant question in this case turns out to be very simple: Can the state supply proof beyond a reasonable doubt that Mehserle formed an intent to use the gun as opposed to his Taser. (Mehserle's) defense will rather be that he believed Grant might be armed, that Grant continued to resist, and that (Mehserle) properly concluded the appropriate response was to use his Taser." Pre-trial hearings have centered on the list of witnesses Rains expects to call up to testify. Among them is John Burris, the Bay Area civil rights attorney who represented the Grant family in a civil suit against BART and won $1.5 million for the family in January. Other key players are expected to take the stand, including Tony Pirone, the former BART cop who pulled Grant off the train and hurled racial epithets at him. Pirone was fired from the BART police force in April just weeks after Marysol Domenici, another BART cop who was at the scene when Grant was killed, was fired. Neither Pirone nor Burris are eager to participate in the trial. Things from the prosecution's side have been much quieter. It will be the first high-profile case for Nancy O'Malley in her tenure as the new Alameda County District Attorney.