Alex Murdaugh speaks with his legal team before he is sentenced to two consecutive life sentences for the murder of his wife and son by Judge Clifton Newman at the Colleton County Courthouse on March 3 in Walterboro, S.C. Joshua Boucher/The State via Associated Press file

COLUMBIA, S.C. — Convicted murderer and former South Carolina attorney Alex Murdaugh has agreed to plead guilty to federal charges he stole millions of dollars from clients, according to court records.

If Murdaugh doesn’t change his mind before standing in front of a judge on Sept. 21, it would mark the first time he admits guilt for any crime in court.

Murdaugh, 55, is serving a life sentence for killing his wife and son at their home two years ago. But he insisted from the witness stand at his trial that he did not kill them and is appealing his double murder conviction.

Prosecutors say he decided to kill them because his millions of dollars of theft was about to be discovered and he was hoping their deaths would buy him sympathy and time to figure out a cover-up.

The federal guilty plea would almost certainly bring prison time, keeping Murdaugh behind bars even if his murder conviction appeal was successful.

Before the killings, state and federal investigators said Murdaugh stole millions from clients who suffered debilitating injuries and who needed money for medical care. He is charged with stealing from his family’s law firm and helping run a drug ring to launder money. Authorities said he asked a friend to kill him on the side of a lonely highway so his son would get $10 million in life insurance. The shot only grazed Murdaugh’s head.

In federal court, Murdaugh faces 14 counts of money laundering, five counts of wire fraud, one count of bank fraud, one count of conspiracy to commit wire fraud and bank fraud, and one count of conspiracy to commit wire fraud. Court records didn’t indicate whether there was an agreement to drop any charges in exchange for a guilty plea.

Each charge carries at least a maximum of 20 years in prison. Some have a maximum 30-year sentence.

Attorneys for Murdaugh didn’t comment on Thursday’s court filing. But they said after his indictment on 22 federal charges in May that Murdaugh was helping federal investigators and the charges would be “quickly resolved without a trial.”

The federal allegations are similar to charges Murdaugh still faces in state court.

They include stealing about $4 million in insurance settlements meant for the family of Gloria Satterfield, a longtime housekeeper who died when she fell at the Murdaugh home, according to the indictments.

Longtime friend and now ex-attorney Cory Fleming helped Murdaugh steal the money, investigators said. Fleming was sentenced earlier this month to nearly four years in prison after pleading guilty.

Other indictments said Murdaugh and a banker friend, Russell Laffitte, worked together to take settlement money out of client’s accounts, prosecutors said. Laffitte was convicted in November of six wire and bank fraud charges. He was sentenced to seven years in prison and is appealing.

Murdaugh is also charged with creating a bank account that had a similar name to a legitimate company that handled settlements to steal money from clients.

He is currently in protective custody at an undisclosed state prison after being convicted in March of the shooting deaths of his 22-year-old son, Paul, killed with shotgun blasts, and 52-year-old wife, Maggie, who was shot several times with a rifle.

Murdaugh is also awaiting trial on around 100 other state charges. Along with the thefts, they also include insurance fraud, a drug and money laundering ring, tax evasion, and theft.

A pretrial hearing on those charges will likely take place the week before the federal guilty plea and would mark Murdaugh’s first appearance outside prison since he was escorted out of the Colleton County Courtroom in handcuffs, shackles, and a jail jumpsuit on March 3.

Murdaugh has been seen publicly only once since then in a batch of photos taken by the camera in his prison-issued tablet computer as the system confirmed his identity so he could use the device to make monitored calls, watch approved entertainment, read books, or take video classes.

The photos showed Murdaugh sometimes shirtless and wearing reading glasses in his cell.

Prison officials initially released the photos under the state’s open records law, but after a brief publicity splash, decided that since the photos were taken for security reasons and not as an official measure, they should not have been released under the Freedom of Information Act.