Richard Cobb never denied using a shotgun to kill a man abducted and shot during a holdup of an East Texas convenience store almost 11 years ago.
A Cherokee County jury sent him to death row and the 29-year-old now is set to die Thursday evening in Huntsville.
Cobb testified at his trial he was forced into fatally shooting 37-year-old Kenneth Vandever because of threats from his holdup partner. That companion, Beunka Adams, was executed last year.
Two women also abducted from the store were shot and left for dead. One of them was raped. But they survived and testified against their attackers.
Attorneys for Cobb are asking the U.S. Supreme Court to stop the punishment. It would be the fourth execution this year in Texas.