Executioners who put to death a Texan man last month have since tested positive for coronavirus, it has emerged.
Orlando Hall died on 19 November inside the Terre Haute prison in Indiana.
Two inmates inside the prison, who are not on death row, have filed a case seeking to stop further executions because they argue that the number of people coming in to the facility for the execution makes them "super-spreader events".
Donald Trump has significantly stepped up the pace of executions ahead of his departure from office in January, and his justice department is pressing ahead with them despite concerns about the pandemic limiting access for lawyers.
The two prisoners, Patrick Smith and Brandon Holm, are suing Bill Barr, the attorney general, in a bid to halt five upcoming federal executions.
In a reply brief filed on Monday, which was obtained by Newsweek, the prisoners' lawyers said that the federal government has yet to reveal exactly how many execution team members have tested positive for the virus since Hall's execution for the rape and murder of a Texas teenager.
They wrote that the federal government's lawyers only noted in a "buried" footnote late in their opposition brief that "some" execution team members have tested positive since the date of the last execution.
"We are not told how many execution team members tested positive ("some"), nor did Defendants choose to have Warden Watson or anyone else address the issue is a sworn declaration," they wrote.
"But the fact that any execution team members tested positive after the most recent execution provides further, compelling evidence of the significant risk that conducting the scheduled executions will spread Covid-19 within FCC Terre Haute (and beyond).
"The risk is not 'speculative.'"
They said the execution team consists of "approximately" 40 Bureau of Prisons (BOP) staff, who all come from outside FCC Terre Haute.
They added that overall, around 50 to 125 individuals travel to the prison complex for each execution – the execution team, state and local officials, witnesses and demonstrators.
Hall's spiritual adviser Yusef Ahmed Nur tested positive following Hall's execution.
Mr Nur said he had close contact with numerous prison employees on the day of the execution, including some who did not wear masks.
After Hall was put to death, Mr Nur said went into the execution chamber to pray for around 15 minutes.
"While I was there, I was approximately four feet away from each of the unmasked executioners," he said in the declaration.
Hall had been tested for the virus on 15 November, four days before he died, and received a negative result.
Mr Nur took one test on 24 November, which was inconclusive.
A second test, on 27 November, confirmed he was positive for Covid-19, he said.
The Terre Haute prison currently has 180 inmates and 18 staff members who are confirmed to have contracted the virus.
The American Civil Liberties Union (ACLU), which has also filed litigation in recent months warning that federal executions would be coronavirus super-spreader events, condemned the federal government for moving forward with them.
