NASHVILLE (AP) — Tennessee Gov. Bill Lee will release more details Monday surrounding why he abruptly canceled the execution of Oscar Smith, delaying his previous plan to reveal the reasons this week, the Republican's spokesperson confirmed.

Casey Black said in an email Tuesday that the governor's office will "be releasing more information and action steps." Lee had previously promised reporters to provide new information this week. However, the governor's office pointed to the pending adjournment of the GOP-controlled General Assembly as a reason to push back divulging execution details.

"I think that's fair to folks who are stretched thin covering final items of import in the legislature and trying to cover this issue with attention to detail," communications Director Laine Arnold said in a follow-up email.

Last week, Lee issued a statement saying there had been an "oversight in preparation for lethal injection" as he granted a temporary reprieve to the 72-year-old Smith. A day later, he said the reprieve was needed because of a "technical oversight," without explaining further.

The governor's office and Department of Correction have since declined to answer direct questions about the planned execution, including whether the execution drugs were compounded, and if so, whether a pharmacist had those drugs independently tested for "potency, sterility and endotoxins" as outlined in the state's lethal injection protocols. The protocol allows the state to use compounded or manufactured drugs.

The reprieve will be in effect until June 1. In the interim, attorneys and death penalty watchdog groups have called for an independent investigation into the matter. To date, the state has declined to say whether they will do so.

Smith was convicted of the 1989 killings of his estranged wife and her two teenage sons. He is the oldest inmate on Tennessee's death row.

He had been scheduled to receive a three-drug injection at a Nashville maximum security prison. In Tennessee, officials use midazolam, a sedative to render the inmate unconscious; vecuronium bromide, to paralyze the inmate; and potassium chloride, to stop the heart.

Lethal injection drugs have been a challenge to obtain for some states as many pharmacies and manufacturers refuse to supply the medications for executions. This has forced some states to explore other execution methods, including South Carolina forging ahead with plans for a firing squad.

In Tennessee, some inmates can choose between lethal injection or the electric chair.