HOUSTON (AP) — A Texas death row inmate whose threatening calls from a smuggled cellphone prompted an unprecedented lockdown of the entire Texas prison system six years ago has lost a federal court appeal.

A three-judge panel of the 5th U.S. Circuit Court of Appeals, in a 2-1 ruling, rejected arguments from Richard Lee Tabler that a competency hearing in which he waived his appeals violated his due process rights. The panel also rejected his argument that he had deficient legal help in his earlier appeals.