BOISE, Idaho -

The Idaho Supreme Court rejected the latest appeal of an Idaho woman convicted of killing her parents in 2003, ruling she failed to show her lawyer was incompetent and didn't demonstrate that new evidence would produce an acquittal.

Sarah M. Johnson was convicted in March 2005 of first-degree murder for shooting her parents, Alan and Diane Johnson, on Sept. 2, 2003.

Johnson was just 16 at the time of the slaying.

In her appeal in Blaine County, a state judge rejected her claims that her conviction should be thrown out.

In the Idaho Supreme Court's decision released Tuesday, justices agreed with the lower court judge, saying Johnson, among other things, failed to show that questioning new witnesses would have produced a different result at trial.

She's serving two life terms.