Police continue to investigate a deadly weekend accident involving a pedestrian and a semi on a highway overpass in Waterloo.

Authorities confirmed that Richard Murphy, 53, of Tama, was struck and killed while walking near the Interstate 380/U.S. Highway 20/Iowa Highway 27-U.S. Highway 218 interchange shortly before 8 p.m. Saturday (Sept. 30, 2017). When police officers arrived at the scene, they found Murphy unresponsive on the roadway.

Waterloo Fire Rescue paramedics initially transported Murphy to a local hospital for treatment. Murphy was later transferred to University of Iowa Hospitals and Clinics in Iowa City, where he died of injuries suffered in the accident.

Investigators are trying to figure out why Murphy was walking on the highway at the time of the accident. According to a Waterloo police press release, the semi's driver reported that he didn't see Murphy walking on the bridge. The driver -- Kent Ridlon, 53, of Klemme -- told responding officers that he initially believed he had hit a deer, authorities said.