A Baltimore court will hear pretrial arguments on Wednesday in the case against six U.S. police officers accused in the death of a black man from an injury in police custody.

The death of Freddie Gray, 25, in April drew worldwide attention when it triggered protests and a day of rioting, arson and looting. The case became part of a national debate on police treatment of minorities in the United States.

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The hearing before Baltimore City Circuit Court Judge Barry Williams will center on defense motions seeking dismissal of the charges and removal of State's Attorney Marilyn Mosby and other prosecutors from the case. Attorneys also will debate whether the officers should be tried together or separately.

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Defense lawyers contend Mosby violated her obligation to assure a fair trial when she announced the charges in an open-air news conference as the largely black city of 620,000 people was in turmoil.

Prosecutors say defense lawyers are trying to divert attention from the officers' role in Gray's death.

Officers arrested Gray on April 12 after a foot chase in crime-ridden West Baltimore. He was bundled into a police transport van while in handcuffs and shackles and was not seatbelted.

Gray suffered a severe spinal injury and died a week later. A medical examiner ruled the death a homicide.

Charges against the officers range from second-degree murder for the driver to manslaughter, second-degree assault and misconduct. Three of the officers are white and three are black.

Prosecutors contend Gray was arrested illegally since he was put in handcuffs before officers found a banned switchblade knife in his pocket.

Besides accusing Mosby of grandstanding, defense attorneys argue that she targeted the corner where Gray fled officers for heightened policing because of drug trafficking, and the designation turns her into a potential witness.

Prosecutors also improperly carried out their own investigation parallel to the official police probe, they say.

Lawyers for the officers argue that Mosby should step aside because her husband is the city councilman for the district where Gray died. Bringing charges would enhance his political career, they say.

The defense lawyers say prosecutors should step aside from the case because they had leaked information about a witness to a television reporter. Mosby also has links to the lawyer representing Gray's family, they contend.

Security has been enhanced around the courthouse in downtown Baltimore, and police leave is canceled. Baltimore has recorded 223 homicides this year, more than for all of 2014, according to a tally by the Baltimore Sun.

Another pretrial hearing is set for Sept. 10 on whether the case should be moved from Baltimore because of publicity surrounding the trial. Trial is scheduled to begin on Oct. 13.