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Robert Bowers, the man accused of killing 11 people during an attack at a Pittsburgh synagogue, pleaded not guilty Monday to 19 additional federal charges of hate crimes, obstruction of free exercise and discharging a firearm.

The total number of charges against him is now up to 63. In November, he pleaded not guilty to 44 charges, which included the murders.

Bowers also requested trial by jury during his appearance Monday at a federal courthouse in Pittsburgh.

Shooting suspect Rob Bowers.

Prosecutors say Bowers, 46, was armed with multiple weapons, including a Colt AR-15 rifle and three handguns, when he opened fire inside the Tree of Life synagogue in the city's Squirrel Hill neighborhood Oct. 27 during a morning service.

The attack left 11 people dead and several others injured, including police officers who were trying to rescue victims and confront Bowers.

Prosecutors said Bowers allegedly talked about his desire to "kill Jews" during the rampage. He also had a history of threatening Jewish communities and posting conspiracy theories about them online.

Bowers faces a maximum possible penalty of life in prison without parole, according to the Department of Justice. Prosecutors have said they will pursue the death penalty, but it first has to be approved by the attorney general.