LINCOLN, Neb. (AP) — The Nebraska Supreme Court has rejected a defense by a Nebraska man who argued an antidepressant caused him to kill his girlfriend in 2002.

Randall Robbins pleaded guilty to second-degree murder in the death of 17-year-old Brittany Eurek and was sentenced to 40 to 60 years in prison.

In an appeal, Robbins argued he should be allowed to undergo DNA testing to show that his body was unable to properly metabolize Zoloft, which he was taking at the time of the killing. His attorney argued that such inability can lead to violent outbursts.

Lower courts last year found Robbins was not entitled to a new trial. On Friday, the state's high court agreed, but said the DNA testing should never have been allowed. The high court says state law allows for DNA testing for prisoners if it could show someone else committed the crime.