The Largo man who police and prosecutors say killed five women across Prince George’s County reached a plea deal Wednesday in the slayings of a mother and daughter — an outcome authorities say finally brings to an end a case that sparked terror across the region before it bogged down in court for years.

As part of the deal, prosecutors agreed not to charge Jason Scott, 30, in connection with the other slayings — although Prince George’s County State’s Attorney Angela Alsobrooks (D) said investigators have “no doubt whatsoever” that he was responsible for them. She said prosecutors offered the man police once dubbed a “serial killer” of mothers and daughters the deal because he was incarcerated on federal charges for life, effectively, and they wanted to spare his victims’ families the emotional toll of multiple trials.

“We have removed, we believe, a ruthless killer from the streets,” Alsobrooks said.

Not everyone was content with the terms.

“We’re not really happy or satisfied with this, but we feel our hands are tied,” said Kirkland Lofton, 50, whose daughter and ex-wife were among those prosecutors allege Scott killed. “I definitely wanted to go through a trial, because I wanted to see the evidence myself. Not only do you have to prove him guilty, but you have to prove it to me.”

As part of his agreement with prosecutors, Scott pleaded guilty under the Alford doctrine to two counts of first-degree murder in the March 2009 slayings of Delores Dewitt, 42, and her daughter, Ebony, 20. Using the Alford plea, he essentially refused to admit that he committed the crimes but acknowledged the strength of the evidence against him.

Prosecutors say he strangled the two women inside their Largo home, then set a stolen car on fire with their bodies inside. He was sentenced to 85 years in prison, also as a part of the plea deal.

Prosecutors said they would not charge Scott in the January 2009 slayings of 45-year-old Karen Lofton, Kirkland Lofton’s ex-wife, and her daughter, 16-year-old Karissa, who were shot to death in their Largo home. They said they also would not charge him in the June 2008 killing of Vilma Butler, 46, in Bowie. She was fatally shot before her home was set ablaze.

Scott was sentenced last year to a century in prison in a separate, federal case in which he was convicted of orchestrating home-invasion robberies, molesting a teenage girl and burglarizing a Maryland gun shop. His Prince George’s sentence will run alongside that, and it is unlikely he will ever be released from prison. But Lofton said that it was important to him to understand why Scott targeted his ex-wife and daughter and that Scott face separate justice for those killings — if he committed them.

“He hasn’t admitted to anything,” Lofton said.

Family members of the Dewitts, though, said they were happy to avoid a trial. Annie Hicks, Ebony Dewitt’s grandmother, said that when prosecutors began a trial against Scott earlier this year — proceedings that ultimately ended in a mistrial — another granddaughter called to testify began suffering panic attacks.

“It was just too much on her,” said Hicks, 66. “Now we can breathe a little bit. Now we can relax a little bit.”

Police and prosecutors had long painted Scott as a cunning serial killer and home invader, one who pored over forensic science textbooks to learn how best to clean up his crime scenes. He often searched for his victims, including the Dewitts, using a computer database he had access to while working at UPS.

“I think he’s the worst that we’ve ever seen,” Alsobrooks said.

Prosecutors and detectives had connected Scott to the slayings with strong — albeit circumstantial — evidence. After he became a suspect in a federal weapons case, he admitted to a series of break-ins across the area of the killings. Investigators found charred remnants of Delores Dewitt’s designer-brand jeans and Ebony Dewitt’s gray sweater at an Upper Marlboro home Scott used as a stash house for the burglary loot. And referring to the killings, he once told a friend, “When they find out this investigation is about me,” before trailing off, prosecutors said Wednesday.

At Wednesday’s hearing, Scott answered just “Yes” or “No” to questions from the judge and declined the chance to speak about the cases. Hicks said she was not surprised.

“I’m just happy,” she said, “that he did plead.”