But on Thursday, the former lawyer was officially charged with their murders.
A grand jury in Colleton County, the area where the pair were killed, indicted Murdaugh, 54, after hearing evidence that he killed his wife with a rifle and his son with a shotgun.
He was charged with two counts of murder and two counts of possession of a weapon during the commission of a violent crime.
"All the efforts of our office and the law enforcement agencies involved in this investigation have been focused on seeking justice for the victims' families," South Carolina Attorney General Alan Wilson said.
Authorities declined to release further information regarding the motive or how they zeroed in on Murdaugh, citing the pending court case.
But Mark Keel, chief of the State Law Enforcement Division, or SLED, said his officers had worked "day in and day out" for 13 months to build the case.
"At no point did agents lose focus on this investigation," Keel said. "From the beginning, I have been clear: The priority was to ensure justice was served. Today is one more step in a long process for justice for Maggie and Paul."
Attorneys for Murdaugh, who have previously said their client did not commit the murders, told BuzzFeed News they were set to release a statement soon.
The charges had been somewhat expected. Alex Murdaugh’s brother, John Marvin Murdaugh, had told the Post and Courier newspaper on Tuesday that agents with the SLED had spoken with family members that day to inform them as a courtesy that they were set to present evidence to a grand jury about Alex’s involvement.
Alex Murdaugh is also already facing a suite of charges related to behavior uncovered in the aftermath of the June 2021 deaths. Most infamously, Alex Murdaugh was arrested and charged almost three months after the deaths and accused of planning his own killing so that his surviving son, Buster, could receive a $10 million insurance payout.
Authorities said he hired a client, Curtis Edward Smith, to shoot him in the head by the side of a rural road. But the bullet only caused a superficial wound and Alex survived, leaving him to call police and falsely report he had been shot by an unknown stranger. Smith was also charged over the incident.
Alex Murdaugh was also later charged with two felony counts of obtaining property by false pretenses for allegedly stealing settlement funds that were owed to the sons of his late housekeeper, Gloria Satterfield.
Last month, he and Smith were also charged over an alleged money laundering and painkiller ring.
Alex Murdaugh had also left his family’s law firm and had his law license suspended after the firm discovered he had misappropriated millions of dollars to fund an addiction to oxycodone, for which he subsequently went to rehab. He was officially disbarred on Tuesday.
Still, Thursday's murder charges are the latest shocking twist in the sordid and tragic downfall of one of the most wealthy and powerful families in Hampton County — a case that has prompted speculation and intrigue across the country.
The bodies of Paul Murdaugh, 22, and Margaret “Maggie” Murdaugh, 52, were first discovered on June 7, 2021, at their family hunting lodge in Islandton.
Alex Murdaugh called 911 shortly after 10 p.m. to report the grisly finding after he said he had returned from Savannah, Georgia, where he’d gone to visit his 81-year-old father, Randolph Murdaugh III, in a hospital.
Autopsies showed Paul and Maggie had each been shot multiple times between 9 and 9:30 p.m. that night.
Randolph III — who had served like his father and grandfather as the elected solicitor for the state’s 14th Judicial Circuit, and who had been awarded the highest civilian honor in South Carolina, the Order of Palmetto — then died three days later from his illness.
As authorities investigated the killings and searched for a possible motive, attention soon turned to a web of deaths that haunted the Murdaughs, whose broader family had amassed large wealth as attorneys working on civil lawsuits in the region.
The Murdaughs had been accused of helping Paul evade legal responsibility for the 2019 death of Mallory Beach, a friend of his who had died when he was allegedly boating at night under the influence of alcohol.
Paul had been charged with drunk driving over the incident in April 2021 and was awaiting trial at the time of his death.
Beach's mother, Renee Beach, had also filed a wrongful death lawsuit against other members of Paul's family, including his grandfather, father, and brother.
As part of their investigation into the Murdaugh killings, detectives also began reexamining the circumstances of the 2018 death of their housekeeper as well as the 2015 death of Stephen Smith, a classmate of Buster’s, who was found dead on a highway but with little evidence to suggest he had been hit by a car.
Satterfield, who had worked for the Murdaugh family for over two decades, was believed to have tripped over the family’s dogs and hit her head.
But Alex Murdaugh allegedly cooked up a scheme whereby he steered Satterfield’s two sons to hire his friend as a lawyer in order to sue his insurer for compensation.
But the two sons said they never received any of the $505,000 settlement and later learned of an additional settlement worth $4.3 million of which they had never been made aware. Instead, most of that money was allegedly transferred to Alex Murdaugh, with $1.4 million paid to his attorney friend as fees.
Alex Murdaugh has been held in jail since a judge denied him bail in October, ruling he could be a danger to himself or others.
"Alex Murdaugh stained our profession," Eric Bland, an attorney representing the Satterfield family, said at the October bail hearing. "He also put a black eye on this state."