Alex Murdaugh, the disgraced South Carolina lawyer found guilty of murdering his wife and son, has long been a thief and liar – but his being a convicted killer is still a shock, his brother has said in the first interview a member of the family has given since the trial.

In an interview with the New York Times, Randy Murdaugh said he remained unsure if Alex murdered his son and wife in June 2021. Randy Murdaugh added that while he respects the jury’s verdict, he has known Alex as a protective father and husband.

“He knows more than what he’s saying,” said Randy Murdaugh, referring to Alex’s lying about the murder. “He’s not telling the truth, in my opinion, about everything there.”

Randy, Alex’s older brother, said in the interview that the pair were not close, despite going to the same college and law school, and working at the family’s law firm together.

“It’s not like there was some problem with our relationship, necessarily,” Randy Murdaugh said. “We just really weren’t alike, so we didn’t do stuff together.”

Weeks after the murder, Randy Murdaugh said that much of the family rallied around Alex, who suggested the killing of his 22-year-old son Paul was due to Paul’s involvement in a fatal 2019 boating accident. Maggie Murdaugh, Alex’s wife, was shot dead alongside Paul.

Months after the murders, Randy confronted Alex about financial records that showed Alex had embezzled millions from the family business. In an emotional conversation, Randy recalled, Alex admitted to stealing, and to a severe addiction to painkillers.

Alex promised never to lie to Randy again, Randy said, but soon broke that pledge. A day later, Alex told police and Randy that he had been shot on the side of the road by an unknown person.

Police later said Alex Murdaugh had arranged to have someone else shoot him, in the hopes that his surviving son Buster could collect his life insurance money.

Randy soon stopped speaking with Alex, who has been charged with stealing more than $8m from the family firm. The pair have not spoken in almost a year.

But in July last year, when Alex was arrested over the murder of his wife and son, Randy re-examined aspects of what he knew about his younger brother.

Randy Murdaugh told the newspaper that the family has dealt with similar uncertainty, given the gruesome nature of the crime and the previous understanding they had of Alex.

“The not knowing,” Randy Murdaugh said, “is the worst thing there is.”

Randy Murdaugh’s interview stands in sharp contrast from statements given by Alex’s defense lawyers, who have said that the Murdaugh family fully believes he did not murder anyone. His lawyers also said the family supports him.

On Friday, Alex Murdaugh was given two sentences of life imprisonment after being found guilty of the murders of Paul and Maggie Murdaugh. The sentences capped a six-week, televised trial in which Alex maintained his innocence, though that was undermined by cellphone video captured by his son that placed him at the scene of the murders shortly before they occurred.

Randy said the Murdaugh family is focused on supporting Buster, who has lost his immediate family. Randy said his life has attracted international attention given his brother’s crimes.

Randy told the New York Times he hoped the trial would give him some closure and an answer about the circumstances around the death of his nephew and sister-in-law, but he said he has not stopped thinking about it.

“I hoped that after the trial, because there’s nothing more that can be presented, that I’d stop thinking about this,” Randy Murdaugh said. “But so far, that has not been the case.”