Personnel at the New York City prison where accused sex trafficker Jeffrey Epstein committed suicide last week have not been initially cooperative with investigators from the Department of Justice, a federal source told Fox News Friday.

Attorney General William Barr sent two senior DOJ officials to personally visit the Metropolitan Correctional Center and speak with staff from the Federal Bureau of Prisons (BOP) in order to gather information on Epstein's death after Barr said officials uncovered "serious irregularities" at the jail, a senior DOJ official told Fox News. The officials have been on site since Thursday and the FBI and the Justice Department's inspector general are investigating conditions at the MCC.

NEW YORK MEDICAL EXAMINER: JEFFREY EPSTEIN'S DEATH WAS A SUICIDE BY HANGING

BOP officials from various regional offices have also been sent to the Manhattan facility to lend their expertise and insight. In addition, a separate BOP "After Action Team" went to MCC earlier this week in an effort to examine what happened the night Epstein died. The use of the "After Action Team" is part of BOP protocol whenever a "significant event takes place at a prison.

Epstein was found dead in his cell on Aug. 10. Earlier Friday, New York City's medical examiner officially ruled the 66-year-old's death a suicide by hanging.

Fox News has also learned that 20 of 21 prison staff posts were filled between the hours of 4 p.m. and 12 a.m. on Friday, Aug. 9, the day before Epstein was found. Of those prison workers, six of them were working voluntary overtime. Between 12 a.m. and 8 a.m. on Saturday, Aug. 10, 18 of 19 staff posts were filled. Of those 18 staffers, 10 were working overtime and all but one of those were doing so voluntarily.

Conspiracy theories swirled following Epstein's death, as many wondered how the wealthy financier could have been able to kill himself in a high-security facility just over two weeks after being placed on suicide watch, though officials later confirmed Epstein had been taken off suicide watch shortly before his death.

Correctional officers did not check in with Epstein for "several hours" before his death, despite being required to visit him every 30 minutes, a person familiar with the situation told Fox News earlier this week.

Jail guards on duty the night of Epstein's death are also suspected of falsifying log entries to show they were checking on inmates every half-hour as required, The Associated Press reported, citing several people familiar with the matter.

Two staffers have been placed on administrative leave and the MCC's warden has been reassigned pending an investigation.

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Late Friday, Epstein's attorneys issued a statement decrying what they described as "the harsh, even medieval conditions at the MCC."

"It is indisputable that the authorities violated their own protocols," Martin Weinberg, Reid Weingarten and Michael Miller said. "The defense team fully intends to conduct its own independent and complete investigation into the circumstances and cause of Mr. Epstein’s death including if necessary legal action to view the pivotal videos - if they exist as they should - of the area proximate to Mr. Epstein's cell during the time period leading to his death.

"We are not satisfied with the conclusions of the medical examiner," the statement concluded. " We will have a more complete response in the coming days

Fox News' Samuel Chamberlain, Jake Gibson and Nicole Darrah contributed to this report.