DAYTONA BEACH, Fla. -- Investigators say they don’t know why a couple found dead outside their still-running SUV had stopped along Interstate 4 near Daytona Beach early on New Year’s Eve with their three young sons safely strapped in their car seats and watching a movie.

A Florida Highway Patrol trooper found the bodies of Daniel Kelsey, 32, and his wife, Heather Kelsey, 30, about 1:30 a.m. on Dec. 31, said Sgt. Kime Montes. She said the trooper was patrolling the stretch of highway that morning and had not seen the SUV when he passed by some 30 minutes earlier.

Volusia County Sheriff Mike Chitwood told The Daytona Beach News-Journal on Thursday that the autopsies found no signs of trauma or foul play. He added that Daniel Kelsey tested “presumptive positive” for drugs and had a “presence of weed” in his urine. The medical examiner’s office hasn’t issued a cause of death because toxicology reports are pending. Chitwood said those reports may show other substances the couple may have taken.

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Investigators said it’s unclear how the Kelsey family wound up stopping on the right paved shoulder of eastbound I-4. The hazard lights on the maroon Ford Freestyle were blinking when the trooper found it. Inside, he found the boys - Aiden, 2, Nicholas, 1, and infant Joseph - watching a movie, Chitwood said.

The Ormond Beach residents were traveling home from Quincy in the Florida Panhandle.

Authorities said relatives of Daniel Kelsey are taking care of the children. John Harrell, spokesman for the Florida Department of Children and Families, told the newspaper the agency is working with local authorities.

“We’re very sensitive to what these children have been through,” Harrell said. “That’s the main priority.”