An 18-year-old Coupeville woman injured in a possible DUI-related accident Monday morning later died that day at Harborview Medical Center in Seattle, the Washington State Patrol reported.

She was identified as Keesha M. Harden.

Trooper Mark Francis said Harden was a passenger in a 2001 Ford Mustang driven by Jeromy Ladwig, 35, of Oak Harbor.

Ladwig was leaving Joseph Whidbey State Park at about 4 a.m., ran the stop sign and was T-boned on West Beach Road by an oncoming 2004 Dodge Dakota driven by Nathan Dee, 26, of Oak Harbor.

Both vehicles ended up in a field. The Dodge rolled onto its side and the Mustang was on its wheels.

Francis said Harden was the most seriously injured, suffering pelvic and head injuries. She was immediately airlifted to Harborview Medical Center but succumbed to her injuries.

Ladwig was transported to Whidbey General Hospital with serious injuries, including a possible back injury and broken finger, Francis said.

The third passenger in the Mustang, 32-year-old Oak Harbor resident Randon Koepke, was injured and transported to Whidbey General Hospital.

Dee was also injured and transported to the hospital by a private vehicle.

Francis said investigators have probable cause to believe that Ladwig was under the influence based on reports that he was driving recklessly in the parking lot prior to the crash.

Also, Ladwig admitted to taking medication before driving, and troopers found “potential drugs and paraphernalia” in the Mustang, Francis said.

Ladwig will be arrested on suspicion of vehicular homicide, Francis said.