CNN  —  Calls to spare the life of Texas death row inmate Robert Roberson are growing, with just over a day left before the state plans to execute him for the murder of his 2-year-old daughter – a crime Roberson’s advocates say did not happen. If he’s put to death Thursday evening, Roberson’s attorneys say he would be the first person in the US executed based on a conviction that relied on shaken baby syndrome – a misdiagnosis in Roberson’s case, they argue, and one they say has been