Nathan Dunlap, 38, center, with attorneys Philip Cherner, left and Madeline Cohen, appear at a hearing at Arapahoe County Court in Centennial, Colo, Wednesday, May 1, 2013. Dunlap's attorneys asked a judge Wednesday to delay designating a week for execution, saying Dunlap's death sentence was meant to be served only after he completed a 75-year sentence for robbery. Dunlap is convicted of killing four people at a Colorado pizza restaurant in 1993. (AP Photo/The Denver Post, Helen H. Richardson, Pool)

DENVER | The mother of a Colorado teenager who was among four people shot and killed in 1993 is pleading with the governor to allow the convicted killer’s execution to go on as planned.

Sandi Rogers, mother of Ben Grant, wrote a letter to Gov. John Hickenlooper asking him not to grant clemency to Nathan Dunlap, who is scheduled to be executed the week of Aug. 18.

This May 1, 2013 file photo shows Nathan Dunlap, 38, with attorney Madeline Cohen, as he appears at a hearing at Arapahoe County Court in Centennial, Colo.  A man convicted of ambushing and killing four employees of a pizza restaurant said Monday he had undiagnosed bipolar disorder at the time and should not be executed. Nathan Dunlap's lawyers made the claim in a formal request to Gov. John Hickenlooper for clemency, also saying Dunlap is remorseful and that he endured severe physical and sexual abuse as a child. (AP Photo/The Denver Post, Helen H. Richardson, Pool, flle)
This May 1, 2013 file photo shows Nathan Dunlap, 38, with attorney Madeline Cohen, as he appears at a hearing at Arapahoe County Court in Centennial, Colo. A man convicted of ambushing and killing four employees of a pizza restaurant said Monday he had undiagnosed bipolar disorder at the time and should not be executed. Nathan Dunlap’s lawyers made the claim in a formal request to Gov. John Hickenlooper for clemency, also saying Dunlap is remorseful and that he endured severe physical and sexual abuse as a child. (AP Photo/The Denver Post, Helen H. Richardson, Pool, flle)
This May 1, 2013 file photo shows Nathan Dunlap, 38, with attorney Madeline Cohen, as he appears at a hearing at Arapahoe County Court in Centennial, Colo. A man convicted of ambushing and killing four employees of a pizza restaurant said Monday he had undiagnosed bipolar disorder at the time and should not be executed. Nathan Dunlap’s lawyers made the claim in a formal request to Gov. John Hickenlooper for clemency, also saying Dunlap is remorseful and that he endured severe physical and sexual abuse as a child. (AP Photo/The Denver Post, Helen H. Richardson, Pool, flle)

“Please, Governor, just sit back, make no decision (to grant clemency),” the letter said. “Please allow us the peace that never hearing Dunlap’s name after August will bring us.”

Prosecutors released the text of the letter on Tuesday.

Hickenlooper’s spokesman said the governor has not decided whether to grant clemency.

Rogers did not immediately respond to a request for comment placed through prosecutors.

Grant was 17 when he and three other employees of a Chuck E. Cheese were ambushed and shot to death. They were cleaning the family entertainment restaurant in the Denver suburb of Aurora after business hours.

Dunlap, then 19, had recently lost a job there. A jury convicted him in 1996 and sentenced him to die.

The U.S. Supreme Court turned down Dunlap’s last guaranteed appeal in February, but his attorneys are fighting on multiple fronts to spare his life, filing new appeals, challenging the way Colorado plans to execute Dunlap and asking Hickenlooper for clemency.

Dunlap would be the first person Colorado has executed since 1997. He has acknowledged killing the four and apologized in a video and written statement released last week. In the clemency request to Hickenlooper, Dunlap’s lawyers said he had undiagnosed bipolar disorder at the time of the shootings.

In her letter, Rogers scoffed at that assertion and said if it’s true, it is not grounds for clemency.

“My niece is bipolar, she has not committed murder, she is also not on medication, she just knows right from wrong,” the letter said.

The letter is signed, “Sandi Rogers, Ben’s mom forever.”