Death row inmate Stephen Michael West did not select a method for his Aug. 15 execution, so the state will kill him using controversial lethal injection drugs if the execution moves forward as scheduled.

Tennessee inmates sentenced to death for a crime committed before 1999 can choose between the electric chair and lethal injection, the state's default method. A spokeswoman for the Tennessee Department of Corrections confirmed that West hadn't picked a method and that a lethal injection was planned.

West is one of dozens of Tennessee death row inmates to challenge the state's three-drug lethal injection protocol.

Medical experts say the first drug, the sedative midazolam, fails to dull the excruciating pain caused by the next two drugs. The inmates argue that leads to unconstitutional torture.

In the last year, two other inmates decided they would rather face the electric chair.

A legal challenge to lethal injection is pending in a federal appeals court, but judges considering similar challenges have declined to stop lethal injection executions here in 2018 and 2019.

West, 56, was sentenced to death for the 1986 murders of a woman and her 15-year-old daughter in their Union County, Tennessee, home.

Wanda Romines, 51, and Sheila Romines were both stabbed to death while their hands were bound behind their backs.

Sheila had been stabbed 17 times in the stomach. At trial, a forensic pathologist said 14 of those stab wounds were consistent with “torture-type cuts.”

West also was convicted of raping Sheila before she died.

West's lawyers have filed a request for mercy with Gov. Bill Lee's office. Lee refused to intervene earlier this year when death row inmate Donnie Edward Johnson asked the governor to stop his execution.

Reach Adam Tamburin at 615-726-5986 and atamburin@tennessean.com. Follow him on Twitter @tamburintweets.