SULPHUR, Okla. (AP) - The Texas truck driver accused of causing a 2014 crash that killed four members of a women's college softball team has been ordered to stand trial.

Russell Wayne Staley is charged with four counts of first-degree manslaughter.

The Oklahoman newspaper reports  that a Murray County judge ruled Thursday that prosecutors had enough evidence for a trial on all four counts.

Federal transportation officials said last year they believe Staley was likely high on synthetic drugs during the crash - although a blood test didn't confirm he had drugs in his system.

The National Transportation Safety Board voted 4-0 that the likely cause of the head-on collision on a highway near Davis, Oklahoma, was the semitrailer driver's incapacitation, "likely stemming from his use of synthetic cannabinoids."