(AP) -- Marking two years since Eric Garner's death became a flashpoint in a national debate about relations between police and minority communities, his mother joined families of more than a dozen men killed by police Sunday at a New Jersey church before laying flowers at her son's grave.

"My heart is heavy today," Garner's mother, Gwen Carr, said as she stood at his gravesite holding a bouquet of yellow flowers and white balloons.

"I love you my son. You'll always be my strength," she said with tears streaming down her face.

Before traveling to the cemetery in a white limousine, Carr joined the Rev. Al Sharpton and dozens of mourners to remember Garner at a church service in Elizabeth. They were joined by more than a dozen families whose children had been killed by police, including the family of Tamir Rice, the 12-year-old who was killed in Cleveland months after Garner.

"We're not fighting for revenge, we're fighting for justice," Sharpton said. "This is not a battle against the police, it's a battle against wrong."

Carr echoed those sentiments saying families of all races need to do more to support each other and called for stronger police-community relationships.

"Let's not wait until tragedy knocks on our door," Carr told churchgoers.

Garner's July 17, 2014, death had been captured on video, which showed him calling out "I can't breathe" as New York City police officers pinned him down and one held him in an apparent chokehold. Garner's dying words became a rallying cry at protests nationwide over police killings of black men amid a nationwide debate over police use of force.

A passer-by's cellphone video shows the 43-year-old Garner, after being stopped by police officers for selling loose, untaxed cigarettes, telling officers to leave him alone and refusing to be handcuffed.

New York Police Department Officer Daniel Pantaleo is seen putting Garner in an apparent chokehold, which is banned under NYPD policy, as he was taken to the ground. Garner, who was heavyset and had asthma, was later pronounced dead at a hospital.

A New York grand jury declined to indict Pantaleo in 2014 and he remains on desk duty while police officials await the outcome of an ongoing federal civil rights probe. Pantaleo's attorney has maintained his client didn't violate Garner's civil rights and that he was performing his duties, which he was trained to do.

Garner's sister, Ellisha Garner, said the wait for the Justice Department to conclude its probe has been trying on the family, but that they'd wait as long as it takes to get justice.

At a church service in Staten Island, New York, Sunday morning, New York City Mayor Bill de Blasio, a Democrat, said society had to overcome "a history of structured racism to move forward." Eric Garner's daughter planned to lead a march through Staten Island later Sunday.