Nashville — Billy Ray Irick's execution remains on track Thursday night at Riverbend Maximum Security Institution. after the U. S. Supreme Court decided not to intervene.

The three-drug lethal injection process is set to commence at 7 p.m. Central time, 8 p.m. Eastern time. The death chamber is located at Riverbend, the state's highest security prison west of downtown.

Irick, 59, was moved earlier this week to a cell within feet of the chamber.

REMEMBERING WHY: 1985 rape and murder of 7-year-old Paula Dyer

MORE: Timeline of Irick's 33-year case

RELATED: Death row inmate Billy Ray Irick asks U.S. Supreme Court to delay execution

While the state's process is in place, it's still possible there could be delays Thursday. Tennessee's last execution in December 2009 was actually supposed to take place hours earlier than the 1 a.m. Central time event.

Defense attorneys are seeking intervention by the U.S. Supreme Court. That's Irick's last hope for a stay.

A lot is no doubt happening behind the scenes Thursday.

The court's clerical staff keeps track of pending executions. A specially designated clerk, sometimes referred to as the "death clerk", is tapped with keeping in touch with the defense, the state and the justices as the hours tick down to the appointed execution time.

Each justice is assigned a region, or circuit, of the country from which appeals might emerge.

MORE: What happens if lethal injection drugs don't work?

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Justice Elena Kagan is Tennessee's "circuit justice", meaning she will be the point of contact for the rest of the court as they ponder whether a stay is necessary in Irick's case.

Justices rarely stay an execution. The process is somewhat secretive, but justices typically confer with their clerks and each other by phone if necessary when an inmate seeks to put off his death sentence.

WBIR will have a journalist present at the execution, as will the News Sentinel and several other Tennessee media organizations.

Witnesses apply and are picked by a drawing process conducted by the state Department of Correction.

Also set to be present Thursday night: Knox County Sheriff Jimmy J.J. Jones. He represents the county in which the killing occurred, according to TDOC.

An attorney for Irick and an attorney for the state Attorney General's Office also will attend, according to TDOC.

WBIR will continue to bring you updates throughout the day and evening.