Trent Davis, 17, was certified as an adult in Greer County Court and received a five-year-deferred sentence after pleading guilty to manslaughter charges in the death of Sierra Cook.

Davis was the driver of a pickup truck that crashed and killed the 13-year-old Cook last year. Davis admitted on Thursday that he was drinking alcohol before the accident. According to reports, Davis had a blood alcohol level of .08 after the Dec. 23, 2008 accident.

In addition to Cook, there were two other teenagers injured in the accident.

As a condition of the plea agreement, Davis must spend 27 days in the Greer County Jail before attending and graduating from a residential military academy offered by the National Guard and the Oklahoma Military Department.

Davis also is required to return to Mangum to complete his high school diploma following the graduation.