The trial lasted almost six weeks. Here’s what to know.

Prosecutors argued that Mr. Murdaugh committed the murders to divert attention from his own financial improprieties, which they said were about to be revealed. Testifying in his own defense, Mr. Murdaugh admitted on the stand that he had stolen millions of dollars from his law firm and clients, but maintained his innocence in the deaths of his wife and son.

Here’s what to know about the case:

Murdaugh was at the crime scene.

After denying for more than 20 months that he was at the dog kennels where his wife and son were found shot to death, Alex Murdaugh confessed that he had lied about his whereabouts. In fact, he testified, he was at the kennels briefly that night, before the murders.

But the admission came only after a video confirming his presence, taken by his son Paul, emerged in court.

Taking the stand in his own defense, Mr. Murdaugh told his lawyer that he had been there for a few minutes, but then had left, laid down at the house, and driven to check on his ailing mother who lived about 15 minutes away. He said he returned about an hour later to find his family dead.

He blamed his lies to the police on paranoia spurred by opiate dependency, as well as his distrust of the South Carolina Law Enforcement Division, a state investigative agency. Mr. Murdaugh testified that he had feared an admission that he was at the kennels before the murders would cause the police to consider him a suspect.

“I lied about being down there,” he said, “and I’m so sorry that I did.”

There is not much physical evidence in the case.

Prosecutors used telephone calls, text messages, videos, car navigation data and even step counts based on cellphone tracking to call into question Mr. Murdaugh’s account of his whereabouts on the night of the killings.

But their case has been hampered by a lack of physical evidence. Investigators haven’t found the family-owned rifle that they say was used to kill Mrs. Murdaugh, nor have they found the shotgun used to kill Paul Murdaugh.

No blood was found on the white T-shirt that Mr. Murdaugh was wearing when police arrived after he called 911 — it would have been covered in blood and body matter, his lawyers argued — and the DNA of an unknown man was discovered under Mrs. Murdaugh’s fingernails.

Mr. Murdaugh’s lawyers sought to portray the police investigation as sloppy, mentioning that some location data on Mrs. Murdaugh’s phone from the day of the killings had been overwritten. Two deputies from the Colleton County Sheriff’s Office admitted that tire tracks from the crime scene had been driven over and stepped on, while another deputy said he had walked near one of the victims’ bodies without covering his shoes.

Defense lawyers also noted that the police had issued a statement in the days after the killings saying that no immediate threat to the public existed. That was an indication, they argued, that the authorities were investigating only Mr. Murdaugh.

One defense lawyer, Jim Griffin, said that the police “failed miserably in investigating this case.” Mr. Murdaugh would have been vindicated, he added, “had they done a competent job.”

Even if he is acquitted, Murdaugh’s testimony will likely hurt him in future cases.

On the day of the killings, the chief financial officer of Mr. Murdaugh’s law firm confronted him, accusing him of pocketing about $800,000 in lawyer fees that he was supposed to have deposited into the firm’s account.

Mr. Murdaugh has since been charged with dozens of financial crimes, with prosecutors accusing him of stealing about $8.8 million in all. He confessed under oath to many of those crimes, including embezzling about $3.7 million in 2019. That’s the same year that his son Paul was charged with drunkenly crashing a boat into a bridge, killing one of his passengers, 19-year-old Mallory Beach.

Mr. Murdaugh has maintained that he believed that his son was targeted by an unknown assailant or assailants because of his involvement in the crash.

The prosecution leaned on Murdaugh’s lies to convince the jury not to trust him.

In addition to an array of financial misdeeds, Mr. Murdaugh testified to a longtime addiction to painkillers and a penchant for lying. The prosecution seized on that admission — how readily, and easily, he had lied to the police, his family and friends — in an attempt to convince the jury that he was lying about not having killed his wife and son.

At one point, the lead prosecutor, Creighton Waters, held up a stack of papers relating to clients whom Mr. Murdaugh stole from.

“Every single one of these, you had to sit down and look somebody in the eye and convince them that you were on their side, when you were not, correct?” he asked while looking directly at the jury.

“What I admit is I misled them, I did wrong, and that I stole their money,” Mr. Murdaugh responded.

In turn, Mr. Murdaugh’s lawyers portrayed his acknowledgment of his lies as a willingness to come clean — that he recognized his shortcomings, but had never been violent and would never have carried out the murders.

Surviving relatives were among Murdaugh’s most ardent defenders — to a point.

Friends and relatives said Mr. Murdaugh was devastated by the killings, with his brother John Marvin Murdaugh testifying that he “would have to create a new word to describe how distraught he was.”

Alex Murdaugh’s surviving son, Buster Murdaugh, testified that his father was “destroyed” and “heartbroken” after the killings. He also said that when he spoke with his father about 20 minutes after prosecutors say the murders took place, Alex Murdaugh sounded “normal” — at a time that Mr. Murdaugh’s lawyers say he had yet to discover the bodies of his wife and son.

But Mr. Murdaugh’s sister-in-law, Marian Proctor, who testified for the prosecution, said he seemed more concerned with protecting Paul’s reputation than with learning who had killed his son. She said she began questioning her brother-in-law’s account about three months after the murders, when Mr. Murdaugh’s firm fired him and accused him of stealing millions of dollars over many years.

When Ms. Proctor asked him who might have murdered his wife — Ms. Proctor’s only sister — and his son, Mr. Murdaugh offered a cryptic response, she said.

“He said that he did not know who it was, but he felt like whoever did it had thought about it for a long time,” Ms. Proctor said. “I just didn’t know what that meant.”