NASHVILLE (AP) — A letter from an attorney for Tennessee's prisons says the state is refusing a death row inmate's request to die by electrocution because his request came too late and because the affidavit he signed was altered.

Edmund Zagorski is scheduled to die by lethal injection Thursday for the murder of two men in 1983. His attorneys have challenged the constitutionality of Tennessee's current three-drug injection protocol and are asking the U.S. Supreme Court to review the case.

In the meantime, Zagorski requested on Monday that he be executed by electric chair. His attorney, Kelley Henry, said Zagorski believes it will be quicker and less painful.

A typed addition to the affidavit states, "By signing this affidavit I am not conceding that electrocution is constitutional." It further states that if Zagorski's appeal of the lethal injection protocol is successful he will go on to challenge electrocution as unconstitutional as well.

In response, Tennessee Department of Correction attorney Debra Inglis writes that Tennessee's execution protocol required Zagorski to inform the department "by close of business on Sept. 27" if he was choosing electrocution over lethal injection.

Inglis also writes that Zagorski's additions to the affidavit invalidate it.

In an emailed statement, Henry said Wednesday that Zagorski remains hopeful the U.S. Supreme Court will intervene to stay his execution in order to consider the constitutionality of Tennessee's execution methods.

She blamed the state for creating "extreme time pressures" that have forced Zagorski to choose between "two absolutely barbaric methods of death."

"It is unconscionable that the state is refusing to let the prisoner choose the method of his execution, which is his right under the law," Henry said.