The trials of four former Minneapolis police officers charged in George Floyd's death will remain split into two proceedings with one starting in March and the other in the summer, a Hennepin County judge ruled.

Hennepin County District Judge Peter Cahill's decision Thursday morning rejected the prosecution's request that he reconsider his ruling from last week that first laid out the plan.

Cahill's ruling came two days after Attorney General Keith Ellison's office filed a motion asking to hold a single joint trial in the summer because more people would be vaccinated against COVID-19 by then. The motion included an affidavit by epidemiologist Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. Osterholm wrote that holding a trial in March could be "extremely dangerous."

"I'm disappointed in the order. Dr. Osterholm's affidavit is substantial and compelling," Ellison said in a written statement. "We are considering our options for next steps."

Cahill ordered the trial split because the county's largest courtroom could not accommodate four defendants and meet social distancing protocol. Derek Chauvin will be tried in Hennepin County starting March 8; J. Alexander Kueng, Thomas Lane and Tou Thao will be tried in one trial starting Aug. 23.

Ellison's prosecutors — Assistant Attorney General Matthew Frank and special attorney for the state Neal Katyal — have asked Cahill two times in three months to retract his rulings on key issues.

In late November, prosecutors asked Cahill to rescind his unprecedented order from earlier that month allowing the trials to be livestreamed outside of the courthouse because COVID-19 would prohibit the public and media from attending in person and would violate the defendants' rights to a public trial. Cahill also promptly rejected that request.

The judge has pointedly questioned the prosecution's approach as well.

Ellison's office first filed a motion in late December requesting one trial starting June 7 because of COVID-19, attaching a seven-page affidavit from Dr. Ezekiel Emanuel of the University of Pennsylvania and a member of President Joe Biden's Coronavirus Advisory Board, to affirm their case.

At a Jan. 7 hearing Cahill noted that while qualified, Emanuel was an oncologist and not an epidemiologist.

Why not use epidemiologist Osterholm, Cahill asked, naming the infectious disease expert who has been at the forefront of the state's COVID efforts.

"It was someone that we, uh, we knew would be an expert in this field," Katyal said, apparently caught off guard.

"I was just curious," Cahill said, noting that Osterholm was "just as busy" as Emanuel.

When prosecutors filed their 27-page motion this week asking Cahill to reconsider splitting the trial, they included a 12-page affidavit from Osterholm to bolster their arguments.

"It could be extremely dangerous to hold a trial for Mr. Chauvin in March 2021. Doing so could have potentially catastrophic consequences for public health," Osterholm wrote. "This is so not simply because of the [relatively small] number of people who would be inside the courtroom, but also because of the large numbers of people likely to be convened outside the courthouse, including demonstrators."

Cahill denied the motion in a filing that did not revisit his reasoning for the split trials.

Thao's attorney, Robert Paule, accused prosecutors at the Jan. 7 hearing of attempting to push back the trial so they could revisit their arguments to prohibit livestreaming. Prosecutors did not respond at the time. Paule, his co-counsel Natalie Paule and Chauvin's attorney, Eric Nelson, had also filed motions to push back the trials in order to deal with copious evidence.

Richard Frase, University of Minnesota law professor and co-director of the Robina Institute of Criminal Law and Criminal Justice, and retired Ramsey County Attorney Susan Gaertner have said attorneys could ask the Minnesota Court of Appeals to review Cahill's trial plan, but it's typically frowned upon.

"The law discourages asking a higher court to review decisions that are made prior to trial about how trial is going to go," Gaertner said after Cahill's first ruling on the matter.

"It's a pretty rare circumstance where a higher court would get involved at this stage."

Joseph Daly, emeritus professor at Mitchell Hamline School of Law, agreed that requests to reconsider would likely have been ill-received.

"Trial judges are there to make sure that due process takes place," Daly said. "Nobody likes to be told they're wrong."

Chao Xiong • 612-270-4708

Twitter: @ChaoStrib