Many of those gathering at Lake Harriet Park in southwest Minneapolis for the sunset memorial wore blue, Ruszczyk's favorite color.
The sound of two didgeridoos being played next to the Australian flag highlighted Ruszczyk's heritage. Plans called for luminarias and a silent walk around the lake at the end of the memorial.
Ruszczyk's fiance, Don Damond, said the two were planning to marry next week.
"Some would call it a cruel irony, but it's just an irony that we would have been on the airplane now, heading for a Hawaiian destination," he said. "It's rather surreal, but the irony isn't lost on any of us."
Officer Matthew Harrity told investigators that he drove to the scene and was startled by a "loud sound" near the squad car, according to Minnesota's Bureau of Criminal Apprehension. Immediately afterward, Ruszczyk approached the driver's side window, and Harrity's partner, Mohamed Noor, shot Ruszczyk through the window, Harrity said.
Both Harrity and Noor are on administrative leave amid the investigation into the shooting.
"Justine, my daughter, was killed by a bullet fired by an agent of the state," John Ruszczyk said at the memorial. "I don't understand. I should have been on a plane to her wedding (rather than) flying to her funeral.
"This is our first visit to Minneapolis," he said. "We should be walking arm in arm down the street."
Beloved spiritual healer
Though she was a veterinary surgeon in her native country, Ruszczyk worked as a spiritual healer, yoga and meditation instructor and life coach in Minnesota. Friday's memorial was hosted by the Lake Harriet Spiritual Community, the organization where she worked.
Her friends have said the concern Ruszczyk showed that night for a possible assault victim was characteristic of her caring nature.
Damon said Ruszczyk, despite being very dirty from the sewer, was overcome with happiness after helping the ducks.
"She came home that night and said, 'I just reached utopia.' She leaned against the wall and looked up. I thought it might be (that) somebody had a breakthrough or something really big. (But she said) 'I rescued eight ducklings.'"
Her father said Ruszczyk coined the term "fuzz therapy" to describe the joy she got from animals.
"She might say to someone, 'You need fuzz therapy,'" he said.
No body camera video
Though the officers were wearing body cameras, they did not turn them on before the shooting, and the squad car camera did not capture the incident, investigators said.
Ruszczyk's death has caused outrage in the United States and Australia and led to the resignation of the city's police chief.
"I am reminded by Justine's death that love is not bulletproof," her father said. "We must work hard to protect the people we love."
"We seek justice for Justine, we are determined to get justice for Justine -- because in getting justice for her, we'll be getting justice for all of us," he said.