A review of surveillance camera footage from inside the Metropolitan Correction Center (MCC) in New York showed that two guards who were supposed to check on Jeffery Epstein every 30 minutes never made their appointed rounds in the hours when the millionaire sex offender died in his cell by apparent suicide, sources familiar with the investigation confirmed to ABC News.

The MCC staff members, who have been placed on temporary leave, are suspected of falsifying log entries to show they made the proper checks on Epstein and other inmates in the Special Housing Unit at the federal lockup in Manhattan, but those log entries have been contradicted by the surveillance footage, the sources said.

The two staff members, who have not been publicly identified, have yet to be interviewed by agents from Federal Bureau of Investigations (FBI) or the U.S. Office of Inspector General (OIG), the two agencies conducting investigations into the circumstances of Epstein's death, sources told ABC News.

A DOJ official tells ABC News that an "after-action" team from the Bureau of Prisons (BOP) is visiting MCC Wednesday, where they're set to look into the way prison officials handled Epstein's detention in the days and weeks leading up to his death by suicide.

On Tuesday, a separate team of BOP psychologists visited MCC to reconstruct how Epstein was able to take his own life in his cell and further probed the decision-making process that led to Epstein being taken off of suicide watch.

These reviews are in addition to the already-ongoing investigations by the FBI and OIG, the official said.

The New York Times reported Wednesday that the two guards had fallen asleep during their shifts and did not check on Epstein for three hours.

Epstein, 66, who was being held at the jail without bail, was found unresponsive in his cell around 6:30 a.m. on Saturday, the Bureau of Prisons said. He was transported in cardiac arrest to a Manhattan hospital, where he was pronounced dead, according to sources.

ABC News has previously reported the staff failed to follow protocol that requires welfare checks every 30 minutes.

His apparent suicide occurred after he was previously found on July 23 unresponsive in his cell with marks on his neck and taken to a hospital, sources with knowledge of the episode told ABC News. He was placed on suicide watch, but removed on July 29 after jail officials determined he was no longer a threat to himself, sources said.

Officials cautioned that the investigation is in its early stages and findings could change.

The two guards who were supposed to be checking on Epstein's well-being were both working overtime, according to law enforcement sources.

Officials also tell ABC News that part of the investigation into his death centers around why Epstein was not assigned a new cellmate after his previous cellmate was transferred out in the hours before Epstein took his own life.

Epstein was being held at the jail without bail after being indicted last month on sex trafficking charges. His death angered many of his accusers, who said they wanted him to be found accountable for the alleged sexual abuse he subjected them to, including some when they were minors.

On Monday, U.S. Attorney General William Barr ordered immediate changes in leadership at MCC in Manhattan in response to Epstein's death, including placing two staff members assigned to Epstein's cell block on leave, pending the outcome of the investigations, according to a Department of Justice spokesperson.

Barr ordered the staff shakeup amid investigations by the Federal Bureau of Investigation and the U.S. Office Inspector General into the circumstances of the multimillionaire sex offender's death by suicide. James Petrucci, the warden at the Federal Correctional Institution in Otisville, New York, will become acting warden at MCC, replacing Lamine N'Diaye.

Barr ordered the Bureau of Prisons to temporarily assign N'Diaye to the Bureau’s Northeast Regional Office, pending the outcome of the FBI and OIG investigations.

The order came one day after Barr rang alarms about "serious irregularities" at the MCC prison and decried the facility's "failure" in being able to secure Epstein.

"We will get to the bottom of it, and there will be accountability," Barr said in remarks to law enforcement in New Orleans Monday.