Mayor Bill de Blasio is treading carefully after police officer Peter Liang was convicted Thursday night of killing an unarmed black man in a public housing stairwell. NY1's Grace Rauh has the story.

Mayor de Blasio does not want to be caught in the cross-fire. After a jury on Thursday found NYPD officer Peter Liang guilty of killing Akai Gurley, the mayor refused to praise the decision or denounce it.

"We respect the judicial process," de Blasio said. "I think the justice system continues to function."

It's a cautious position that may be smart for de Blasio, even if it fails to satisfy the police reform advocates who backed his bid for City Hall, or the police union leaders who have clashed with him since he took office.

"This verdict will have a chilling effect on every New York City police officers that goes out on patrol, because what happened here was a terrible, tragic accident," Patrolmen's Benevolent Association President Pat Lynch said. "And they criminalized it."

"I don't believe it will have a chilling effect," the mayor said.

In November 2014, the rookie police officer Liang had his gun out when patrolling the stairwell at the Pink Houses, a public housing development in Brooklyn.

Liang said the gun accidentally went off after he was startled by a sound.

The Brooklyn District Attorney said the officer had his finger on the trigger and pulled. Gurley was in the dark stairwell and was struck by the bullet after it ricocheted off the wall.

Having police officers make their way through public housing stairwells, a practice known as vertical patrols, is coming under fire.

Last week, two police officers on a vertical patrol in the Bronx were shot.

"Vertical patrols are necessary," said de Blasio.

Reverend Al Sharpton likened the practice to Stop and Frisk this week, and said its use must be examined closely.

Lynch, who is in the midst of a contract fight with the mayor, said the city needs to ensure officers on patrol are safe.

At the very least, Lynch said, public housing stairwells need to be properly lit.

"He's careful with his words, but we are looking for actions as well," Lynch said.

On police issues, the mayor is once again trying to walk a very fine line.