A 70-year-old Vietnam veteran convicted of killing his in-laws was executed on Thursday in a case activists and attorneys claimed was fraught with “false testimony and questionable experts,” The Houston Chronicle reports. Billie Wayne Coble was convicted of capital murder in 1990 after allegedly kidnapping his estranged wife and killing her parents and brother before trying to kill himself. He was put to death by lethal injection at the state penitentiary in Huntsville, where several of his family remembers were reportedly thrown out after causing a commotion. Coble's son, Gordon Coble, began kicking and screaming as the procedure was carried out and began banging on the window to the execution chamber as his dad closed his eyes, according to local news station KCEN-TV. The Texas Board of Pardons and Paroles had reportedly turned down Coble's plea for clemency on Tuesday, despite critics questioning the fairness of Coble's trial. “That Coble will be executed on such discredited testimony is unconscionable,” Brian Stull, an ACLU attorney who previously handled Coble's case, wrote before his execution.