The wedding ceremony between Allgier and Herrera will take three to five minutes, Lt. Dinero said.
"The people getting married don't have any contact," he said. "It's done through a glass window. They come in, sign the papers, say the vows, and leave."
Dinero said that no family members are allowed to attend the ceremony. As a maximum security prisoner, Allgier will be in hand and feet shackles, wearing a "standard jail issued jump suit."
Herrera said that she had no plans to wear a wedding gown.
"That would just be asinine to wear a wedding dress when I can't even kiss my husband," she said. "I'm the type of girl that has tattoos on my hand. You wouldn't catch me in a dress anyways."
Instead of exchanging rings, she said, the couple, who have tattoos on their faces, will tattoo each other's names on their ring fingers. They are hoping for a "honeymoon" in a state prison that allows conjugal visits, because the Salt Lake County Metropolitan Jail does not.
"We're hoping hoping that [Allgier] will get moved to a prison that allows conjugal visits." she said. "It's also for the conjugal visits, is why we're getting married so quick."
Future Groom Faces Death Penalty
DeHaan said that she doesn't care about the personal life of her father's alleged murderer.
"If somebody wants to marry him, that's their own thing," she said. "I just want him off the road and safe from hurting anyone else."
Allgier was being escorted June 25, 2007, by corrections officer Anderson to the University of Utah Medical Center in Salt Lake City where the prisoner was scheduled to have an MRI. After Allgier's handcuffs were removed, he grabbed Anderson's gun and allegedly shot the officer to death, according to the Utah County Sherrif's Office.
"It was horrible, horrible. Very devastating," Anderson's daughter, DeHaan, said. "It was hard to believe that it would happen to him."
The Salt Lake County district attorney's office notified the court last March of its intention to seek the death penalty for Allgier for the alleged 2007 murder of Anderson, according to the Associated Press.
Allgier's attorney was not immediately available for comment to ABCNews.com.
"If his crime in the law is punishable by death, to me that's acceptable," DeHaan said. "Whatever serves justice, [my family and I] say is right."
Herrera, whose family disapproves of her marriage to Allgier, she said that if her fiancee is convicted and receives the death penalty, she would have the marriage annulled. "I can't let that weigh on my heart," she said. "I want a life and I want to get on with my life, so that's something that's not in the cards for me."
For now, she worries about her Allgier's recent dramatic weight loss in jail: 40 pounds because of stress from his impending trial, she said.
His lawyers have filed a motion to add supplemental nutrition to his meals Aug. 20.
After that comes the request to remove his tattoos, some of which will be covered up rather than erased.
"I'm not saying he's going to come out with a bunch of flowers all over him," Herrera said, "but he's going to come out a changed person."