Gerardo Pena Garza, 54, died Wednesday afternoon after leaving the eastbound lanes of Interstate 84, going through the median and crashing in a marshy area off the westbound lanes.
Pena, from Othello, Wash., was stopped minutes earlier by an Idaho State Police trooper and given a warning for a publicly unspecified infraction.
After the traffic stop, which happened about 2:05 p.m. at Milepost 29.5 near Caldwell, Garza continued east in his 2004 Dodge Caravan. About a half-mile east of the initial traffic stop, the same trooper watched Pena's vehicle make an abrupt turn from the far right lane and move to the left lane, across the median and westbound lanes into the marshy area.
The trooper found Pena unconscious. The driver was taken by ambulance to West Valley Medical Center in Caldwell, where he was pronounced dead.
The Washington State Police notified Pena's family of his death.
One westbound lane of was blocked for approximately 90 minutes while crews worked to clear and investigate the scene.
The crash is under investigation by Idaho State Police.