UPDATED | March 3, 2016 5:57 AMBy Brian New

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DENTON (CBSDFW.COM) – A North Texas mother hopes she may finally learn the whereabouts of her child, who has been missing for almost two decades.

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Jan Bynum remembers the day her daughter, Kelli Cox, disappeared as if it was yesterday; even though it was 19 years ago. “That day is crystal clear,” she said reflecting. “My last words to Kelli was, ‘I love you, honey. Have a good day.  I’ll talk to you this afternoon.’”

Cox was last seen on July 15, 1997.  The 20-year-old University of North Texas student had stopped at a gas station in Denton, across the street from the police station near downtown, to make a call on a pay phone.

There were leads and tips, day after day, month after month, year after year, but Bynum has yet to find any answers. “All along, through the years my plea has been [that] I know someone knows something,” she said.

That “someone,” Bynum now wonders, could be William Reece. On Wednesday, Reece, a convicted kidnapper and suspect in multiple missing women cases, showed investigators in southeast Houston where to dig.

Still in handcuffs, Reece could be seen standing with investigators as two excavators dug more than six feet into the ground. Officials went to the private property based on tips given by Reece. In this case, police say they’re searching for missing 17-year-old, but believe other bodies could be in the area too.

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A few months after Cox went missing in 1997, her mother said the name William Reece came up as a person of interest. But nothing materialized at the time.

Last month the Denton Police Department sent cold case investigators down to Houston to speak with a “person of interest” in the Cox case.  The department has not publicly identified exactly who that person was.

Bynum said she doesn’t know if Reece had anything to do with her daughter’s disappearance. “If he does my plea would be for him to tell whoever needs to be told so we know what happened to our daughter.”

What has kept Bynum going over the years has been her granddaughter. “They look identical,” she said, looking at pictures of her daughter and granddaughter side-by-side.

Cox’s daughter, Alexis, was 19-months old when her mother vanished. She’s now 20-years-old, the same age her mother was when she went missing.

“You get up every day and say is this the day she knocks at the door, she calls on the phone, or is this the day the police department is going to call me,” Bynum said. “I want to know what happened to my daughter.”

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