Updated

Attorneys for a Virginia inmate scheduled to be executed next month are challenging the state's plan to use lethal injection drugs from a secret compounding pharmacy.

Attorneys for Ricky Gray said in a federal complaint filed Wednesday that there is a risk that Virginia "will chemically torture" the man to death when it uses compounded drugs to execute him on Jan. 18.

Documents obtained by the AP show that Virginia has purchased enough of the sedative midazolam and potassium chloride, which stops the heart, from the compounding pharmacy for two executions. Under a new state law, officials are withholding the pharmacy's identity.

Virginia uses a three-drug lethal injection protocol.

Gray was convicted of killing Bryan and Kathryn Harvey and their 9-year-old and 4-year-old daughters in Richmond in 2006.