Guilty Plea Ends 4-Year Court Battle in Drunk-Driving Deaths

In a surprise move Tuesday, a Ventura County woman pleaded guilty to gross vehicular manslaughter in the 1989 drunk-driving deaths of three young men, ending a lengthy legal battle that had gone as high as the U.S. Supreme Court.

Diane Mannes, who admitted killing the three young men when her car swerved off the Ventura Freeway’s Conejo Grade while she was intoxicated, will serve no additional prison time as part of the plea agreement.

Mannes, 38, was convicted of injuring two other youths in the crash and served about half of a four-year prison term.

But a jury deadlocked on three second-degree murder charges. When the Ventura County district attorney’s office sought to retry Mannes, a federal court blocked the proceeding. U.S. District Judge A. Wallace Tashima ruled that the trial judge had in effect acquitted Mannes of murder when he wrote that there was insufficient evidence to support a murder verdict.

The Constitution’s prohibition against double jeopardy protects defendants from being tried twice for the same offense, Tashima said.

After the U.S. 9th Circuit Court of Appeals upheld Tashima and the Supreme Court declined to hear the case, Ventura County prosecutors proceeded with charges of gross vehicular manslaughter.

But Superior Court Judge James M. McNally ruled in February that the double-jeopardy rule applied to any homicide charges stemming from the case, meaning that manslaughter charges could not be brought either.

The district attorney’s office appealed McNally’s ruling but decided to drop the appeal as part of Tuesday’s plea agreement.

“It’s the best approximation of justice obtainable in light of the previous judicial rulings,” Deputy Dist. Atty. Kevin G. DeNoce said of the plea agreement. “It’s the next best legal charge we could proceed with.”

The agreement calls for Mannes to receive a suspended prison term of three years and eight months and five years probation. Mannes could be sent to prison if she violates terms of the probation, which stipulate that she abstain from alcohol.

Linda Oxenreider of Camarillo, the mother of one of the victims, supported the plea agreement but said the resolution of the case came “about four years too late.”