(CNN)Prosecutors dropped one misconduct in office charge against Baltimore police officer Lt. Brian Rice as his trial began Thursday. Rice is one of six officers charged in relation to the death of 25-year-old Freddie Gray.
Prosecutors dropped the misconduct charge, for allegedly failing to arrest without probable cause, after acknowledging that Rice was not directly involved in Gray's arrest.
Rice, who was the highest ranked officer charged, still faces charges of involuntary manslaughter, second degree reckless assault, reckless endangerment and a remaining misconduct in office charge for failing to secure Gray with a seat belt inside a police vehicle.
Prosecutors said during their opening statements that Rice's status as a supervisor meant he held culpability for Gray's death.
"He was in charge," said Chief Deputy State's Attorney Michael Schatzow. "Because of the decisions that Lt. Rice made, Freddie Gray is dead."
Rice was one of the three bicycle officers who encountered Gray on April 12, 2015. Shortly thereafter, Gray suffered a fatal spinal cord injury while in police custody.
The state says Rice's decision-making and authority over other officers present contributed to Gray fatal injury.
"This defendant is not an inexperienced officer," Schatzow said, arguing that Rice knew the proper procedures of detaining and seat-belting Gray. "He knew and ignored it," Schatzow said.
Defense attorneys for Rice contended that Gray's death was accidental and Rice used his reasonable judgment and discretion in his decision-making, particularly in not seat-belting Gray during times they were in direct contact.
"Evidence will show that Mr. Gray's death was a tragic, freak accident that no one could have foreseen," Defense Attorney Chaz R. Ball said.
Ball also said Gray was kicking and screaming and continued to be belligerent and combative when Rice was present. The large, growing crowd and the confined space in the back of the transport wagon all informed Rice's decision not to restrain Gray with a seat belt.
Freddie Gray van driver cleared on all charges 03:22
Rice elected for a bench trial Tuesday, which means the verdict will be decided by Judge Barry Williams instead of a jury. Williams is the same judge who acquitted Officer Edward Nero and Officer Caesar Goodson on all charges related to Gray's death.
The state began calling witnesses Thursday, including Dr. Carol Allan, the medical examiner who performed Gray's autopsy. She ruled Gray's death a homicide by neck injury.
Allan said there were two components that contributed to Gray's manner of death: failure to use a seat belt and failure to get medical attention when Gray acknowledged that he needed it.
"If a seat belt had been used, the type of injury that Mr. Gray sustained would not have occurred," Allan said.
Allan told Michael Belsky, another defense attorney for Rice, under cross-examination that witness statements contributed to her ruling. Belsky then brought up the statement of Officer William Porter, another officer charged in relation to Gray's death. Porter said Gray did not look like he was injured at the point when Allan ultimately ruled that he was.
Allan replied by saying that Porter is not a trained medical professional. She said she read his statement, but used other factors and her own training to determine when Gray suffered his fatal injury.
Porter's own trial ended in a mistrial and he is set to be retried in September. Officers Alicia White and Garrett Miller are still awaiting trials later this year.
