The United Nations Human Rights Office slammed Alabama‘s impending execution of an inmate by way of nitrogen gas next week and called on the state to halt the scheduled execution.

Kenneth Eugene Smith was convicted for a 1988 murder-for-hire killing of Elizabeth Sennett and is set to be executed by the state on Jan. 25. Ravina Shamdasani, spokeswoman for the U.N. high commissioner for human rights, warned going forward with the method “could amount to torture” in a lengthy statement released on Tuesday.