TULSA, Oklahoma - Sources in Arkansas confirm the cold case task force went there to serve a warrant for a man's DNA Tuesday, December 12, in the unsolved murder of Dena Dean. 

News On 6 has been covering this story since the 1998 murder and obtained the exclusive new information.

Two days before 16-year-old Dena Dean disappeared, she told her boyfriend she was pregnant, even though she wasn't. 

Documents say investigators initially developed her boyfriend and his father as suspects in the case.

Investigators got a tip two months ago that also points to the boyfriend's uncle and that's the man they took DNA from Tuesday.

Documents say Dena was last seen at Marvin's grocery store on West Skelley Drive by a friend of hers who says Dena was going to the parking lot to meet her boyfriend.

Dena's parents found her car at Marvin's later that night with Dena's purse still inside it.

Witnesses say they saw a person who looked like Dena interacting with people in two different vehicles that night.

Her body was found six days later in a field not far away. The medical examiner ruled it a homicide, but couldn't determine exactly how Dena was killed.

"You don't get over it. You learn how to go on, but, you never get over the loss of a child," said Diana Dean, Dena's mother.

Documents say the investigation initially focused on the boyfriend and his father as possible suspects, but no arrests were ever made, no charges were filed and the case went cold.

In 2016, the Tulsa County Cold Case Task Force - made up of retired investigators - took another look at the case.

"They're working hard and doing all this on their own expense and don't have to do this, they've volunteered and they've given me more hope than I've had in the last 19 years," Diana Dean said. 

Documents say investigators got a lead in October that the boyfriend's uncle participated in the murder. Documents say the investigation of a suspect vehicle developed traces of unidentified male DNA that wasn't the boyfriend or his father but was a male relative. 

That led current investigators to get a warrant to collect the uncle's DNA for testing.

Dena's family has long believed people in West Tulsa know more about this case than they're saying and they say, now is the time, as this case is finally unraveling, for people to come forward and talk.