The Utah Board of Pardons granted parole for Swapp in April, saying he has accepted responsibility and shown remorse for his role as a leader in the confrontation.
The 13-day standoff unfolded after Swapp detonated 87 sticks of dynamite at the LDS center in Kamas on Jan. 16, 1988. Police followed tracks in the snow to the nearby compound, where Swapp's father-in-law, John Singer, had been killed years earlier.
In 1979, police shot Singer after he pointed a gun at officers trying to arrest him over his refusal to send his children to public schools. Singer, 48, practiced polygamy and had been excommunicated from the LDS church, which he held responsible for his legal problems.
Swapp, who had married two of Singer's daughters, barricaded himself in a log house on the compound with 14 others, including nine children.
More than a hundred officers gathered in the snow surrounding the compound, using tactics in the ensuing days such as flashing lights and circling loud snowmobiles around the property in the middle of the night to psychologically wear the clan down.
Inside the compound, members of the Singer-Swapp clan fired shots at police floodlights and used mirrors and a lantern to flash the message "Cops not telling truth," in crude Morse code.
The standoff ended in a gun battle that killed Lt. Fred House, a dog handler with the state Department of Corrections.
House was shot by Singer's son, John T. Singer, after a dog was released toward Swapp when officers moved in to capture him.
John T. Singer was imprisoned on state and federal charges related to the standoff and was released from prison in 2006.
Swapp, who was injured in the shootout, served 17 years in federal prison on related charges before starting a Utah sentence in 2006. He's been serving time in Arizona after officials decided not to house him in Utah because of his ties to a state officer's death.
At a parole hearing in September, Swapp showed regret for his actions and said the years he had spent behind bars shaped his beliefs and let him focus on the pain he'd inflicted on other people.
"What I've come to learn is that how I acted was completely wrong," Swapp said. "I should not have done what I did. If I could go back and redo it, I certainly would ... My recourse now, if I was back there, would be to simply find another place to live."
At the hearing, he read an apology, including a statement directed at the House family.
A parole board member reported that House's widow, Ann House, said she felt Swapp had been imprisoned for enough time and accepted his apology.
After he's released, Swapp said he plans to join his wife Charlotte in Fairview, Utah.
When reached by phone on Friday, Charlotte Swapp declined to comment to The Associated Press about her husband's pending release.
At the September hearing, Swapp told the parole board that he plans to use his freedom to atone for his actions and transcend the notoriety associated with the standoff.
"I am fully determined to live a life of peace, to be a blessing to my fellow man, (so) when I finally am buried and people reflect upon my life, I want it to be not what happened in the year 1988 ... but the man that I've become since I got out of prison," Swapp said. "So I can be a blessing to my fellow man and that when people talk about me, it will be with love in their hearts, not as some radical, not as some fanatic, but as someone who truly represented the teachings of Christ. That's what I want with all my heart."