NEW YORK (Reuters) – As Akai Gurley bled to death in a New York stairwell, the police officer who fired the fatal bullet was upstairs arguing with his partner about whether to call in the incident, prosecutors said at the start of the officer’s trial on Monday.

New York Police Department Officer Peter Liang is charged with manslaughter and other crimes in the Nov. 20, 2014, shooting inside a Brooklyn public housing project.

“Akai Gurley is dead today because he crossed paths with Peter Liang,” Brooklyn Assistant District Attorney Marc Fliedner told jurors in his opening statement.

Defense lawyer Rae Koshetz said Liang fired his gun accidentally and that he had no idea the bullet had ricocheted off a wall into Gurley’s chest in the “pitch-black” stairwell.

“This was a million-to-one possibility,” she said.

The death of the 28-year-old Gurley, an unarmed black man, added to nationwide tensions over police use of force against minorities. Liang, 28, is Chinese-American.

Just days after the incident, a grand jury declined to indict a white police officer for killing black teenager Michael Brown in Ferguson, Missouri. Less than two weeks later, a New York grand jury cleared a white officer in the chokehold death of Eric Garner.