New York City's first lady Chirlane McCray, in an essay published in Essence magazine, said she mourned Eric Garner's death last July in Staten Island as a "step backward" for the community.

McCray wrote about having attended the previous month an NYPD-organized meeting of grandmothers left to care for grandchildren whose parents have been murdered or incarcerated -- an initiative that gave her hope for police-community relations. Then, Garner died after a cop placed him in an apparent chokehold during an arrest over a petty offense.

"And I mourned the step backward as the community reflected on the death of yet another unarmed Black man," wrote McCray, who is black. "Like many, I wondered, What will it take to build a relationship of trust between communities of color and the police who serve them?"

The essay was penned before the Dec. 20 ambush slayings of police officers Wenjian Liu and Rafael Ramos by a gunman who alluded to Garner in an online vow to kill cops.

The rare public reflection by the guarded McCray on the Garner incident was published in Essence's "Black Lives Matter" issue, which goes on newsstands Friday. The phrase was a rallying cry of protesters following the deaths of Garner and Michael Brown, a black Ferguson, Missouri, teenager killed by a white police officer, and after grand juries declined to charge police in either case.

McCray acknowledges that police have a "tough, tough job. In the face of real physical danger, the officers are required to maintain their professionalism and composure." She also cited work by her husband, Mayor Bill de Blasio, to provide training and tools -- including body cameras -- to the NYPD and to decrease low-level marijuana arrests and the use of the stop-and-frisk tactic.

The essay does not mention the couple's 17-year-old biracial son, Dante, who de Blasio said the couple has cautioned "to take special care" in interactions with cops.

The remark was seized on by police unions as unsupportive of the NYPD. Patrolmen's Benevolent Association President Patrick Lynch said after Liu and Ramos' deaths that de Blasio had blood on his hands.

In an addendum to her essay, McCray called the slain officers, who were posthumously promoted to detective first grade, "two selfless men who embodied the NYPD's highest ideals."

She ended on a forward-looking note, saying the Grandmother's LOV (or Love Over Violence) project was expanded in September to all five boroughs.

"I believe our progress depends on our recognizing the thread of humanity that binds us together," she wrote.