CHICAGO (CBS) — Nearly six weeks after a developmentally disabled woman and her toddler nephew went missing, police in Gary, Indiana, have issued regional Silver Alert for the pair.

Diamond Bynum, 21, and her 2-year-old nephew, King Walker, disappeared on July 25, after they apparently went for a walk. While there have been a number of reported sightings since, no AMBER alert was ever issued in the case.

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On Wednesday, Gary police issued a Silver Alert, a public notification about a missing person, typically used when the person is elderly, or suffers from a mental disability.

Bynum has limited mental capacity, and a condition that makes her want to eat constantly. Her family moved to Gary from Hammond in February, and police have said she is not yet familiar with the area around her new home in the 500 block of Matthews Street.

Bynum’s father, Eugene, said he’s glad police finally put out an alert.

“I really don’t know why it took this long. I’m just happy that it’s finally happened. I just hope that it’s not too late,” he said.

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He said he’s remaining optimistic his daughter and her nephew will be found.

“We’re not going to stop looking for them. So we have to keep strong, so we can do whatever we need to do to find them,” he said.

The family has helped search dozens of vacant buildings in Gary, and police have investigated several leads, but so far nothing has panned out.

“We’re holding up as well as can be expected. The thing is that, of course we’re sad. We miss our children,” Eugene Bynum said.

Gary police have previously said they want to question a person of interest, identified as Terrance D. Williams, also known as Dollar.

Williams is approximately 5 feet, 9 inches tall and 145 pounds. He is known to frequent the area of 2200 Georgia Street in Gary as well as the 800 block of Pennsylvania Street, police said.

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Eugene Bynum said he was following up on a tip Wednesday, after someone claimed Diamond and King were seen in Hammond.