Prosecutors seeking to put a former Minneapolis police officer in prison for the death of George Floyd bolstered allegations on the use of force but stopped short of calling the killing intentional in a move legal experts said could ease the path to a conviction.

Minnesota Attorney General Keith Ellison on Wednesday added a more serious second-degree murder charge against Derek Chauvin. Prosecutors last week accused Chauvin of third-degree murder and second-degree manslaughter. He could serve up to 40 years in prison if convicted.

Three other officers who were with Chauvin at the time of Floyd's death — Thomas Lane, J. Alexander Kueng, and Tou Thao — all face two counts: aiding and abetting second-degree murder and aiding and abetting second-degree manslaughter. Two of those officers helped keep Floyd pinned to the ground.