6-year anniversary of disappearance of Gary woman Diamond Bynum and nephew King Walker

CHICAGO (WLS) -- Joshua Williams refuses to give up hope that his son King Walker and his aunt Diamond Bynum will come home safely one day.

"I'm still hopeful that my son is coming back so it's kind of hard to move forward in my life," said Ariana Walker, King Walker's mother.

Sunday marks six years since their disappearance and the family is still asking for the public's help to find them.

"If anyone's got some video on a camera, on a cellphone of where these kids went to, please come out and say something," said family friend George Ivey.

The pair went missing on July 25, 2015, while visiting a relative's home in Gary, Indiana.

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Bynum, who has special needs, was 21 at the time. Her nephew was just 2 years old.

"I can't keep going on like this not having no answers. I need an answer. I need to know what happened. I need closure," said their relative Lashann Walker.

As the family clings to the belief that they are still alive somewhere, their frustration with the investigation grows as the case goes cold.

The family said they've decided to look to Chicago to once again plead for help to find their missing relatives.

Relatives have floated the idea of hiring a private investigator but haven't been able to get the needed police records because it's still an active case.

No one from the Gary Police Department could be reached for comment.

Gary Mayor Jerome Prince expressed his sympathy in a statement saying police are following all leads.

"I can't possibly know the exact pain being endured by the Walker and Bynum families. As a father and grandfather, I sympathize with the frustration and fear caused by not having King and Diamond by their sides. I join them in their continuing prayer for the safe return of their loved ones. Also, I can assure them the Gary Police Department is continuing the investigation into their missing loved ones, and we will exhaust any and every lead."

The family has also enlisted the help of the National Center for Missing and Exploited Children. An age-progression image shows what King may look like now at 8 years old. Diamon would now be 26. At the time of her disappearance, she walked with a limp.

In the meantime, there are prayers of hope.

"If he's out here watching the TV screen, this is your dad talking to you. I love you," said Joshua Williams, King's father.