(WRCB) - A Knoxville man has been convicted of killing a Chattanooga woman in 2008.

A Knoxville jury has convicted Micah Johnson in the death of Carrie Daugherty.  Johnson was sentenced to life in prison with the possibility of parole after 51 years.

Johnson never disputed murdering Daugherty in 2008, with a brick, shovel and rope.

His attorneys argued his mental illness is documented, and he was insane at the time.

Prosecutors said mental illness doesn't equate insanity, and said Johnson worked a full shift without problems just before the murder.

They also say he was waiting for Daugherty outside her home, indicating premeditation.