Papillion – Investigators are still trying to determine who provided alcohol to four high school girls killed in earlier this year when the car they were in ran off a county road south of Omaha and crashed in flames.

Sarpy County Sheriff Jeff Davis said last Monday that investigators think two school-age people may be the culprits.

“It’s possible we have an idea of where the alcohol came from and we just can’t prove it because we don’t have the right person to come forward and say, ‘Yeah, that’s what happened,’” Davis said during a news conference at the sheriff’s office in Papillion.

Investigators have already conducted 40 interviews, he said, and stand ready to do more in order to find the supplier.

The car the girls were in June 17 traveled 90 mph before it hit a guardrail and burst into flames just over 3 miles west of Springfield, authorities said.

Killed in the crash were 16-year-old driver Abigail Barth; Alexandria Minardi, 15; and Kloe Odermatt and Addisyn Pfeifer, both 16. Another teen, Roan Brandon, survived. All attended Gretna High School.

A July report said Barth had a blood-alcohol content of 0.09, above the legal adult limit of 0.08. Nebraska law sets the legal limit for those under 21 at 0.02. Investigators have said that, other than Pfeifer, all the girls had alcohol in their systems.

Some people have asked why authorities keep pressing to close the case but, without meaning to, keeping the pain alive for the girls’ parents, the sheriff said.

“We can’t let that go,” Davis said, adding it’s his and his investigators’ jobs to see that nothing like this ever happens again.