Witnesses say the driver who died when his car hit a tree in Nanuet yesterday may have been speeding at the time of the crash. Police say the accident happened at around 11 p.m. near the intersection of Lawrence Street and Drayton Place. According to authorities, 25-year-old Shane Thompson, of Spring Valley, slammed his 1999 Honda Accord into a tree, splitting the car in half. He was pronounced dead at the scene. Investigators say they are unsure what caused the accident, but are looking into eyewitness accounts that point to speeding as a possible culprit.It is unclear whether alcohol was also a factor.