Before the sentence was announced, prosecutor Creighton Waters asked the judge to impose a maximum of consecutive life sentences.

Waters called Alex Murdaugh “a cunning manipulator, a man who placed himself above all others, including his family, a man who violated the trust of so many, including his friends, his family, his partners, his profession. But most of all, Maggie and Paul.”

“Both of them, like everyone else, was unaware of who he really was,” he said.

“I've looked at his eyes. And he liked to stare me down as he would walk by me during this trial. And I could see the real Alex Murdaugh when he looked at me,” Waters said. “The depravity, the callousness, the selfishness of these crimes are stunning. The lack of remorse and the effortless way in which he lies, including here sitting right over there, in this witness stand. Your honor, a man like that, a man like this man, should never be allowed to be among free, law-abiding citizens again.”

Alex Murdaugh gave a brief statement to the judge before sentencing, saying, “I’m innocent. I would never hurt my wife, Maggie, and I would never hurt my son, Paw-Paw.”

South Carolina Attorney General Alan Wilson said he hopes no one forgets the victims at the center of Alex Murdaugh's trial, even as the case became "sensational" and "grabbed the attention of the world."

"At the end of the day, two people were brutally murdered, they lost their lives, a family was destroyed, a legacy was torn asunder and there’s been a wake of victims going back decades, and we want to put the attention on them and let them know that their voice can be heard," Wilson told ABC News' George Stephanopoulos in an interview Friday on "Good Morning America."

Wilson said the disgraced lawyer has "been weaving a tangled web of lies for decades," which the South Carolina attorney general said was evident when Murdaugh took the stand to testify in his own trial, after cellphone video had placed him at the scene minutes before the crime occurred.

"For so long, he's been able to manipulate people and bend them to his will because he's so good at what he does," Wilson said. "He was a master at manipulating and communicating with juries and I believe when he took the stand, that was his last closing argument. He had done this for so long, he believed that he could get what he wanted out of this jury. And I think when he took the stand, he confirmed for many of those jurors what they had heard in that video -- that he was a liar."

Wilson said he was "pleasantly surprised" when he learned that the jury had returned a verdict in less than three hours and hoped it was a good sign.

"I didn't know what to think," he recalled. "I respect the process too much to be that confident, but I was guardedly optimistic when they came back as quickly as they did."

Wilson said the guilty verdict sends a message to those "who question the criminal justice system" and who think "it doesn’t apply fairly and equally to all people."

"We are here to say that it does, that no one is above the law in South Carolina and when you brutally murder your wife and son, you will be held accountable no matter who you are," he added.

The South Carolina attorney general thanked the authorities, investigators and prosecutors behind the case, saying: "They made this conviction possible."

ABC News chief legal analyst Dan Abrams said he expects Alex Murdaugh will be sentenced to life in prison without the possibility of parole, since prosecutors have said they will not seek the death penalty.

"I'm not expecting there to be much debate," Abrams said Friday on "Good Morning America."

"He's now in a tough spot, because he can't really now accept responsibility just after testifying for all these days and talking about how he didn't do it," Abrams noted. "What he could say is similar to what he said on the stand, which is: I regret, I did bad things to people, I'm sorry about that, I hurt people that I cared about, with sort of these broad allusions to the financial crimes without actually admitting anything with regard to the murders."

Abrams said he thinks it was a mistake on the defense team's part for Murdaugh to testify.

"To some degree, you could argue he had to take the stand," he explained. "Suddenly, there's evidence that he's there at the crime scene despite the fact that he's saying he wasn't there."

"So now it doesn't have to be him per se, but somebody's got to explain what he was doing there minutes before the crime occurs," he continued. "In retrospect, was it a mistake? Sure, because if he hadn't taken the stand, he might've been better off. I said at the time I thought it was a mistake for him to take the stand. But they did have to do something to explain why his voice was clearly there at the crime scene minutes before Maggie and Paul were killed."

Mark Keel, chief of South Carolina’s Law Enforcement Division, said that “in the end Paul was a little detective,” likely alluding to Paul Murdaugh’s cellphone video that placed his dad, Alex Murdaugh, at the crime scene minutes before Paul and his mother were murdered.

“SLED agents have worked tirelessly for the past nearly 21 months to ensure justice was served for Maggie and Paul,” Kent said in a statement Friday. “It was all done under constant pressure and scrutiny. I want my folks to know how incredibly proud I am to be their Chief.”

He added, “Today is not the end, it’s the next step in the long road to justice for every person who has been victimized by Alex Murdaugh.”

“This case serves as notice to anyone who aided or assisted Alex Murdaugh in committing any crime that justice will be sought,” Kent said.

Alex Murdaugh faces about 100 other charges for allegations ranging from money laundering to staging his own death so his surviving son could cash in on his $10 million life insurance policy. Alex Murdaugh has admitted to stealing money from clients.