Yuba County authorities have all but closed their investigation into a horrifying raceway crash that took the life of 14-year-old Santa Rosa boy and a Grass Valley race car owner last month.

The Yuba County Coroner's Office will be ruling that the March 16 deaths of Marcus Johnson and Dale Richard Wondergem Jr., 68, were accidental, though no one particularly expected any other result, Undersheriff Jerry Read said.

Routine toxicology tests on the young driver, Petaluma High School senior Chase Johnson, Marcus Johnson's cousin, have yet to be returned, but there is no suspicion the tests will show any alcohol or drug use, Read said.

Chase Johnson, 17, an up-and-coming sprint car racer, was rounding the dirt track during warm-up for the Marysville leg of this year's California Sprint Car Civil War Series when he lost control of his car at about 90 mph that Saturday night.

His car careened off the track, smashed through a fence into the pit area and struck and killed Wondergem and his own cousin, a Rincon Valley Middle School eighth-grader and budding racer himself.

Chase Johnson later told family members that the steering wheel of his race car suddenly came loose in his hands, causing him to lose control of the vehicle.

Read said investigation of the car did not turn up any evidence of a malfunction or problem with the steering wheel. But race car steering wheels are equipped with quick-release levers that permit drivers to remove them when they get in and out of the cockpit, and it was not possible to tell if it might have come loose somehow, Read said.