About 20 percent of the 204 killers on Ohio’s death row are expected to try to escape execution by claiming they are mentally retarded. Public defender David Bodiker says his office will have filed 36 to 40 mentally retarded petitions by the Monday deadline set by the Ohio Supreme Court. Bodiker says he believes there is substantial evidence of mental retardation in those cases. The U. S. Supreme Court ruled last year that it was unconstitutional to execute the mentally retarded. A spokesman for the Attorney General’s office says it’s unlikely that there is that many legitimate mental-retardation cases.