(Milwaukie, OR)  --  Police in Milwaukie are calling off the search for a vehicle that hit and killed a two-year-old boy.  Investigators say autopsy results for Jack Barrett indicate that speeding was not a factor in what they believe was an accident.  Because of that, they believe the collision likely did not cause much damage to the truck, and the driver may not have even been aware of what happened.  Police are still working to determine all the circumstances that led to the child's death.