CNN
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For a year and a half, Alex Murdaugh denied he was anywhere near where his wife, Maggie, and 22-year-old son, Paul, were brutally killed.

But it was one of his victims – his son – who would provide key proof after his death that legal experts say exposed his father’s web of lies and ultimately led to his conviction in the double homicide.

“It is ironic, in the end, that it was the victim, Paul Murdaugh, who solved his own murder,” Dave Aronberg, state attorney for Florida’s Palm Beach County, told CNN Thursday night.

Murdaugh, a now disgraced former South Carolina attorney, was found guilty Thursday of fatally shooting his wife and son and, a day later, was sentenced to life in prison without the possibility of parole. He has maintained his innocence.

The key proof came from a video, which Paul recorded moments before he was gunned down and killed. It appeared to show one of the family’s dogs near the kennels on their property. It also captured Alex Murdaugh’s voice in the background – and placed him at the scene of the crime.

The video, which Murdaugh didn’t know existed before the trial, marked the crumbling of his alibi and left him no choice but to take the stand and explain why he lied multiple times to authorities about his whereabouts, legal experts told CNN.

Murdaugh, while denying he killed his wife and son, testified he lied about where he was because of paranoid thoughts stemming from his yearslong drug addiction to opioid painkillers, as well as his distrust of investigators. While on the stand, he also confessed to more lies, admitting in court he had stolen millions from his law firm and clients over roughly two decades.

He told the jury that despite his repeated past deceptions, he was honest about one thing: he did not kill his family.

But jurors did not believe him.

And in a case with little to no direct evidence linking Murdaugh to the scene, South Carolina’s top prosecutor credited the video clip for the quick conviction by the jury.

“This was a circumstantial evidence case but what people have to understand is that circumstantial evidence is just as powerful as direct evidence,” South Carolina Attorney General Alan Wilson, who was part of the prosecuting team, said Friday. “I think the kennel video hung him.”

“The jury saw how he was trying to manipulate them, saw how he was lying and they read through it, and they heard the kennel video and they made the right decision.”

Craig Moyer, one of the jurors who helped convict Murdaugh, told ABC News in his first public interview that it took less than an hour for the group to reach a unanimous decision.

The video is what convinced him.

“I could hear his voice clearly,” Moyer told ABC. “And everybody else could too.”

Moyer said he was surprised Murdaugh admitted he lied about the video, but, he added, he still did not believe the defendant was being truthful about what happened on the night of June 7, 2021.

Murdaugh was “a good liar,” Moyer said, “but not good enough.”

“When he took the stand – that is, Alex Murdaugh – that was his opportunity to state his claim. It was a very hard sell, however,” said criminal defense attorney and CNN Legal Analyst Joey Jackson. “As much as you deny, deny, deny being at the kennels, you took the stand because it came out that you were there. Cell phone data put you there, car data put you there, in addition to the fact that your own voice put you there, by virtue of what your son recorded.”

“I think by virtue of what that juror said, clearly he was of the view that … (Alex Murdaugh) was continuing to lie, the evidence was clear and that he was guilty,” Jackson added.

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The video was recorded by Paul at 8:44 p.m. on the night of the killings, according to testimony during the trial.

Colleton County Coroner Richard Harvey testified he estimated Maggie and Paul’s time of death to be around 9 p.m. – though he said it’s possible the pair could have been shot any time between 8 p.m. and 10 p.m.

After admitting he lied to authorities about where he was that night, Murdaugh said he did briefly go to the kennels and left roughly around 8:47 p.m.

He later visited his mother and found Maggie and Paul’s bodies when he returned home, Murdaugh testified.

Murdaugh told the court that as his longtime addiction evolved, it often caused him to go into “paranoid thinking.” Those paranoid thoughts were triggered on the night of the homicides, he said, when investigators tested his hands for gunshot residue and asked him about his relationship with his wife and son. Murdaugh claimed that was why he lied.

“All those things, coupled together after finding them, coupled with my distrust for (the South Carolina Law Enforcement Division) caused me to have paranoid thoughts,” he testified. “I wasn’t thinking clearly. I don’t think I was capable of reason. And I lied about being there, and I’m so sorry that I did.”

“Once I told the lie, I told my family, I had to keep lying,” he told the court.

Former prosecutor Sarah Ford told CNN that Murdaugh “really had no choice other than to take the stand and clarify” the video at the kennel.

“And the jury did not buy that clarification. He was lying long before he walked into that courtroom, long before he took the stand and that jury believed that he was lying to them on that stand,” Ford said.

After his sentence, Murdaugh was released to the South Carolina Department of Corrections.

He was processed Friday evening at a reception and evaluation center in Columbia, the department said in a news release. As part of that process, he had his head shaved, a standard procedure for inmates processed into the system, department spokesperson Chrysti Shain said.

Murdaugh will next undergo medical tests and a mental health and education assessment, the release added.

Over the next month and a half, department officials will take into account the results of his tests and assessments as well as his crime and sentence in deciding which maximum-security prison he will be sent to, the department said.

Correction: A previous version of this story misstated which video captured Alex Murdaugh’s voice. It was a video taken on Paul Murdaugh’s phone at the family’s dog kennels.