Attorney General Chris Koster launched his second television ad Tuesday, this time highlighting the 2009 death penalty sentence of a man convicted of murdering a Missouri state trooper.

The ad focuses on the 2005 murder of Missouri State Highway Patrol Sgt. Carl Graham. Koster's office handled the prosecution of the case and pushed for the death penalty upon conviction.

Koster, a Democrat running for his second term, is a long-time supporter of the death penalty. Earlier this year he asked the Missouri Supreme Court to set execution dates for 19 death row inmates. In August, the court denied his request, citing the legal questions that still surround the use of propofol for lethal injections. A lawsuit currently pending in Cole County court contends the use of propofol violates the constitutional ban on cruel and unusual punishment.

Koster is running against Republican Ed Martin and Libertarian Dave Browning.

Martin released his first ad of the general election campaign on Monday.

Here's Koster latest ad: