Cedar Rapids police are trying to find out why a man walked onto Interstate 380 Thursday, where he was struck and killed by a construction truck. Police says the accident happened around 7:45 A.M. in the northbound lanes of the I-380 and 33rd Avenue southwest overpass. The man identified as 34-year-old John Stepalla of Cedar Rapids was struck and killed by a truck driven by 42-year-old Jeffery Wolf of Iowa City. Police are conducting a toxicology examination on Stepalla, and are also investigating the possibility it may have been a suicide. Cedar Rapids police are asking that anyone who might have information in the case to contact them.