Scott Lee Kimball was released from prison to become a paid FBI informant, married the unsuspecting mother a young woman he had allegedly murdered, and spent their honeymoon camping and off-roading in an area where her daughter's body was buried.
Kimball also used the alias "Hannibal" to befriend a prison cellmate's girlfriend who vanished, allegedly murdered by Kimball and buried in a remote Utah canyon.
Kimball has been in jail since 2005 on related charges, but grisly new details emerged in an arrest affidavit released Tuesday in Boulder, Colo. The court papers charge Kimball with being a serial killer, accused of murdering both missing women as well as a third woman and his own uncle.
Kimball, already sentenced to 48 years in prison on related charges, is being held on $2 million bail. He will be arraigned on the new charges Thursday.
His alleged victims include his uncle Terry Kimball, Jennifer Marcum, Kaysi McLeod and LeAnn Emery. Authorities believe the murders took place between August 2003 and September 2004.
The plight of families searching for the missing women and the slow pace of the investigation was the subject of a John Quinones story on "20/20" last year. Families also criticized the FBI for not keeping a better eye on Kimball after he was released to work as an informant.
Parents of the dead women say Kimball's arrest has been too long in coming, but are thankful it's finally happened.
"I'm ecstatic," said Kaysi's father Rob McLeod told ABC News. "Happy is the wrong word, but I can't think of another one."
Jennifer Marcum's father Robert said he's glad that Kimball has finally been charged in the crimes, and says he'll make the trip from Illinois to Colorado for Kimball's arraignment. Even though Kimball is expected to plead guilty, Marcum says he'll believe it when he sees it.
"The real thing will come when he's convicted of murder. Until then, I'm not getting my hopes up," Marcum said. "This guy has buffaloed people for so many years."
Marcum's remains have never been found. Her father hopes Kimball will have something to say about that in court.
"I want to hear if he'll say something we don't know, and I'd really like to know" he said. "She is really missed and loved and we are so unhappy it's unbelievable."
Kimball convinced authorities to let him out of prison in December 2002 in order to work as an informant in a murder-for-hire plot involving former cellmate Steven Ennis and his girlfriend, Jennifer Marcum, the 25-year-old mother of a 4-year-old boy. A few months later, Marcum disappeared.
According to the affidavit another former cellmate, Brett Lee Gamblin, told police that Kimball asked Gamblin if he thought breast implants could be traced. Gamblin wondered why anyone would be concerned with breast implants when a body could be identified by fingerprints or teeth.
Despite repeated searches, Marcum's remains have never been found.
In August 2003, Kaysi McLeod went missing.
Kimball Honeymooned Where He Buried Bride's Daughter
Kimball told a former cellmate that a member of the Sons of Silence motorcycle gang had hired him to kill McLeod, 19, because she was set to testify as a witness in a drug trial against the gang's leader.
Kimball claimed, the cellmate says, that in order to get close to Kaysi, he started dating her mother Lori. After Kaysi's disappearance, Kimball married Lori during a ceremony in Las Vegas.
They apparently honeymooned at an RV park near Kremmling, Colo., and went off-roading in a remote area.
The affidavit says that after Kaysi's remains were located in 2007, "Lori McLeod stated that she believed the site where she was taken to camp, in September 2003, was in the immediate area of the site where Kaysi McLeod's remains were eventually located."
Cell phone records show Kimball was in the area where Kaysi's body was found at the time she disappeared, according to the affidavit.
Kimball is also suspected in the death of LeAnn Emry, the girlfriend of another Kimball cellmate named Steven Holley.
LeAnn's father, Howard Emry, discovered that through Holley his daughter had been introduced to Kimball. LeAnn apparently knew Kimball, who insisted she only call him "Hannibal," was dangerous.
"If Hanable (sic) knew I was talking to you he'd have me killed in a second," she emailed her cousin on Jan. 10, 2003. "Plus, he'd have you killed too."
Kimball, the affidavit says, befriended LeAnn and helped her write bad checks and misuse credit cards until her abandoned car was found near Moab, Utah, on Jan. 30, 2003.
In March of this year, Kimball led investigators to the site where LeAnn was buried in a box canyon in eastern Utah. A .40 caliber bullet fragment found at the scene of LeAnn's remains matched a gun Kimball owned in 2003.
In August 2004, Kimball's uncle Terry also disappeared. The affidavit says Kimball spread a story that Terry had won the Ohio State Lottery and moved to Mexico with a stripper named Ginger. A year after disappearing, Terry supposedly sent an email from Mexico claiming he was doing well there and never wanted to come back to the United States.
Scott Kimball Sentenced to 48 Years as Habitual Offender
The affidavit says a search of Scott Kimball's computer found a login for a Yahoo email account for Terry Kimball. Other records show that Scott Kimball wrote bad checks in Terry's name and used his uncle's credit cards to pay for hotels and a rental car during a trip to Alaska in September 2004.
The FBI later found bloodstains at a Broomfield, Colo., house where Scott Kimball once lived. DNA tests showed that the blood was a match for Terry Kimball.
In January of 2009, Scott Kimball provided authorities with a handwritten map to a location west of Vail Pass in Colorado. Investigators had to wait until the snow melted in June, but were able to locate the remains of Terry Kimball at the precise location Scott Kimball had drawn on his map.
Kimball was already in custody before his arrest on murder charges. In December 2008, he was sentenced to 48 years in prison on theft and habitual offender charges. At that time, the affidavit says he signed a "memorandum of understanding" that he would plead guilty to one count of second-degree murder, but be immune to further prosecution for other murders.
A condition of the memorandum was that Kimball lead authorities to the remains of Jennifer Marcum, LeAnn Emry, and Terry Kimball. Kaysi McLeod's remains had already been recovered without Kimball's help.
Catherine Olguin with the Boulder District Attorney's office told ABC News that she could not comment on why Kimball is being charged with two counts of second-degree murder given the memorandum of understanding. Prosecutors plan on holding a press conference after Kimball's arraignment Thursday.