HOUSTON (AP) A man on death row for an East Texas robbery a decade ago where three people were shot, one fatally, has lost a federal court appeal. The decision moves 28-year-old Richard Cobb a step closer to execution.

Cobb argued to the 5th U.S. Circuit Court of Appeals that letters from a jailhouse informant to Cherokee County prosecutors improperly were withheld as evidence in Cobb's trial.

The informant also testified against Cobb at his capital murder trial for killing 37-year-old Kenneth Vandever during the robbery of a store in Rusk in 2002 and abducting, shooting and wounding two female clerks. The New Orleans-based appeals court ruled late Friday the letters were immaterial in the trial outcome.

Cobb's companion in the robbery, Beunka Adams, was executed last month.