Oklahoma to execute man convicted of killing horse trainer OKLAHOMA CITY (Reuters) - Oklahoma is scheduled to execute on Tuesday a man convicted of stabbing and beating a horse trainer to death in a case of mistaken identity. Johnny Dale Black, 48, is scheduled to die by lethal injection after 6 p.m. Central Time (0000 GMT) at a state prison in Oklahoma. He would be the sixth person executed in Oklahoma this year. Black was convicted of first-degree murder and battery in the 1998 killing of Bill Pogue, 54, a horse trainer from Ringling, Oklahoma. He had been looking for someone else, according to court documents. Black was one of five men who went out hunting for a man who had threatened one of the five because he had been having an affair with the man's soon to be ex-wife, according to court documents. The group was looking for the man's black sport-utility vehicle and instead encountered Pogue, who had gone to a convenience store with his son-in-law, Richard Lewis, to buy chewing tobacco and was driving home in a black SUV. The group of five men stopped their compact car in front of the SUV and attacked Pogue and Lewis, beating them and stabbing them more than 10 times each, according to court documents. Pogue died later from his wounds, while Lewis survived the roadside attack, according to court documents. The morning after the fight, Black fled to Texas, where he was later arrested and confessed to the crime, according to court documents. Black said he did not remember stabbing Lewis and said he was afraid for his brothers, who were part of the group in the fight, and did not intend to kill Pogue. Black was also convicted of manslaughter in 1984 in the shooting death of Cecil Martin. If the sentence is carried out, Black would be the 39th person executed in the United States this year, according to the Death Penalty Information Center, down from 43 executions in each of the past two years. The number of executions in the United States has been on a decline overall since 1999, when 98 people were executed. Reporting by Heide Brandes; Editing by David Bailey and Cynthia Osterman