The garden memorial in Ivy Hill Park is highlighted by a raised, triangular planter in honor of the three victims: Hightower, 20-year-old Dashon Harvey and 18-year-old Terrance Aeriel.
Aeriel's sister, Natasha, 19, was shot in the head but survived, and is represented with a plaque that reads "With Thanks for the Loving and Courageous Heart of Natasha Aeriel."
The three were shot execution-style next to a wall in back of the Mount Vernon School, and at least two of the victims were slashed with a machete. The crime sent shock waves across Newark, a city where gun violence had become commonplace in recent years.
Since then, violent crime has decreased in the city, highlighted by a 43-day stretch in 2008 without a homicide, something that hadn't happened in Newark in more than 40 years.
Mayor Cory A. Booker said the triple slayings struck a chord among residents that continues to reverberate.
"Unfortunately that summer is indelibly marked on the consciousness of our community, but the real story is not that the physical lives of these children fell, but that their spirit lives on and continues to have a transformative impact on our city," he said.
Carolyn Jackson, a friend to the Aeriel family who represented them at the ceremony, called the memorial an "incredible, awesome expression of love." She said Natasha, who is living at an undisclosed location under the state's witness protection program, has not returned to school but is in good spirits.
Shalga Hightower and Harvey's father, James, lauded the efforts of Essex County Executive Joseph N. DiVincenzo Jr., who was a driving force behind the memorial.
"I memorialize my son every day in my heart," Harvey said. "I do not need a memorial to rectify my son's spirit, because it's in me every day. But it's lovely to have something like this where we can come and unify ourselves and to rejoice in the spirit of this community."
Hightower and the Aeriels had been friends since elementary school and played in the marching band at West Side High School. Terrance Aeriel, known as T.J., took Hightower to the school prom in 2006, chauffeured by his sister.
On Monday, Shalga Hightower wore a T-shirt bearing a picture of her daughter and Terrance Aeriel together.
At Delaware State University the Aeriels met Harvey, a social work major who was also a musician. Hightower, who was working two jobs at the time of her death, had planned to attend the school last fall.
Six suspects were arrested within two weeks of the attack and face murder charges. Authorities have said the crime began as a robbery attempt before escalating to violence.
On Monday, Shalga Hightower urged the crowd of several hundred people, which included students from the Mount Vernon School, where the killings too place, to use the tragedy to make positive changes.
"I ask everyone within the sound of my voice: Let us not look back in anger or forward in fear, but let us look around in awareness," she said.
