Kimball arrived handcuffed at his hearing in a wheelchair, wearing a red jail suit and glasses. He is in a wheelchair because he is unable to stand. It is unclear why.

The courtroom hearing was packed and family members of the victims, LeAnn Emry; Kaysi McLeod; Jennifer Marcum; Terry Kimball, Scott Kimball's uncle, lined both sides of the room.

Scott Kimball stared straight ahead, showing no emotion.

His mother was in the room as was his ex-wife Lori. McLeod's father, Rob, was also present along with Emry's father, Howard.

"He is a monster with no conscious and he should be treated as such," Emry, whose daughter's body was found in a rural area near Moab, Utah, said. "I'm aware he has no remorse for the pain he's caused my family which is considerable."

Marcum's father Bob also talked to 9NEWS about his loss.

"Scott Kimball has destroyed our lives," Marcum said. "Our hope is that he has a long life in prison so that he can think about what he has accomplished in his life. And maybe someday reveal how many other families he has also hurt."

"We will never forget Jennifer until the day we die," he said. 

Kimball's plea agreement provides a 48-year sentence for count one and 22 years for count two. The sentences will be served consecutively. 

The family members were joined by more than a dozen law enforcement members who have contributed to the investigation.

"Since he will not get the death penalty that he deserves, Mr. Kimball must be locked up for the rest of his life. Only then will society be safe from this evil person," Emry said.

As part of the plea deal, Scott Kimball cannot have any contact with the families of the victims, with the exception made for some family members of Terry Kimball.

The Boulder County District Attorney's office also agreed not to prosecute Scott Kimball for a handful of forgery offences as part of the plea agreement.

"I was happy and relieved. Up until he said, 'I'm guilty. I plead guilty.' I wasn't sure if he was going to go through with it," Rod McLeod, Kaysi McLeod's father, said.

Kaysi McLeod's remains were recovered in a remote area of Jackson County in June 2008.

The remains of Emry were found in the Book Cliffs of southeastern Utah on March 11.

Remains thought to be those of Terry Kimball were found near Vail Pass in June.

The remains of Marcum have not been found.

Investigators believe Scott Kimball, who used to work as an FBI informant, is responsible for the disappearance of each person from the Denver area.

Until now, he had not been charged with any of the disappearances.

After the sentencing, Scott Kimball's spokesman told reporters that Scott Kimball says he did not act alone in the murders.

However, he refused to name other people involved.

The FBI says it has no information to suggest anyone other than Scott Kimball killed the four people.

Scott Kimball pleaded guilty to a federal gun possession charge on Jan. 22, 2008. Federal Judge Marcia Krieger ordered him to serve 70 months in a federal prison on that charge.

Scott Kimball is currently being held in the Boulder County Jail.

He has previously been convicted of seven felonies.