Arkansas death row inmate Latavious Johnson died of unknown causes at the Varner SuperMax prison on Friday afternoon, according to the state’s department of corrections.

The U.S. Supreme Court agreed on Friday to hear an appeal by Alabama officials of a judicial decision that a man convicted of a 1997 murder is intellectually disabled - a finding that spared him from the death penalty - as they press ahead with the Republican-governed state's bid to execute him.

Justices will consider the case that revolves around the role of multiple IQ scores in determining an Alabama murderer’s eligibility for capital punishment.