Tennessee Gov. Bill Lee on Tuesday said he will not intervene to stop the execution of Harold Wayne Nichols.

Nichols, 64, is scheduled to die by lethal injection on Thursday for the 1988 rape and murder of Karen Pulley, a 20-year-old student at Chattanooga State University.

Nichols confessed to killing Pulley as well as raping several other women in the Chattanooga area. Although he expressed remorse at trial, he admitted that he would have continued his violent behavior had he not been arrested. He was sentenced to death in 1990.

Nichols’ attorneys had sought to have his sentence commuted to life in prison, citing the fact that he took responsibility for his crimes and pleaded guilty. His clemency petition stated “he would be the first person to be executed for a crime he pleaded guilty to since Tennessee re-enacted the death penalty in 1978.”

In a statement emailed late on Tuesday, Lee said, “After deliberate consideration of Harold Wayne Nichols’ request for clemency, and after a thorough review of the case, I am upholding the sentence of the State of Tennessee and do not plan to intervene.”

In a recent interview, Pulley’s sister, Lisette Monroe, said the wait for Nichols’ execution has been “37 years of hell.” She described her sister as “gentle, sweet and innocent,” and said she hopes that after the execution she’ll be able to focus on the happy memories of Pulley instead of her murder.

Nichols’ attorneys issued a statement saying they are “deeply saddened and gravely disappointed” by Lee’s decision to deny clemency.

“Wayne has spent decades taking accountability for his actions, working to transform his life, and being an extraordinary person who is loved and trusted by correctional officers, faith leaders, and many in his community," they wrote.

Nichols broke into Pulley’s home, raped her and beat her on the head with a 2-by-4 board. Pulley suffered massive brain injuries and died the next day.

Nichols was arrested several months after Pulley’s murder for unrelated rapes and burglaries in the Chattanooga area. He confessed to raping several victims in Chattanooga over a two-month period prior to Pulley’s slaying. He pleaded guilty to the rapes for two victims, but went to jury trial for two others and was convicted.