The pedestrian killed in a fatal hit-and-run accident Tuesday morning in Arlington was a 62-year-old veteran from the Boston area, police said.

Police said Robert Shepard was struck by a vehicle at about 5:30 a.m. and thrown under the I-395 exit ramp at Route 110 near the Pentagon.

A car was initially seen on the side of the road near the man. Police are investigating whether that was the vehicle that hit Shepard, or a passer-by who stopped to help.

Some roads in the area, including around Arlington National Cemetery, remained closed Tuesday morning while the Arlington police department’s critical accident squad investigated. All were reopened just before noon, authorities said.

Police said Shepard victim was from Lawrence, Mass. On June 29, his girlfriend called local police in Lawrence to say he was missing, and that he was endangered because he has a history of mental illness, authorities said.

This item has been updated.

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