TULSA, Oklahoma - Cold case investigators got a search warrant Tuesday in the 1998 Dena Dean murder case. It's the third warrant they've gotten in the past week. 

New documents show investigators have interviewed six confidential witnesses recently who've provided crucial details about the case, leading investigators to focus on Dena Dean's boyfriend, the boyfriend's father and uncle as suspects.

They say it all hinges on Dena telling her boyfriend she was pregnant, two days before she disappeared. 

Documents say confidential Witness 5 told investigators when the boyfriend's father learned Dena claimed she was pregnant, he rushed back from Missouri to West Tulsa to confront Dena at Marvin's Grocery Store. Her car was found at Marvin's later that same night but Dena had disappeared.

"A lot of people know information on this case," said Sgt. Mike Huff. 

Documents say Witness 5 told investigators the boyfriend's father and uncle killed  Dena and were in a red truck at the time. 

Witness 5 gave a detail of the crime scene that had never been released that matched a crucial fact in the case.

"This is the most rapid cold case I've ever been involved with and that's 40 years worth," said Sgt. Huff. 

Witness 1 said a woman told him the boyfriend's father showed up at her house the night Dena disappeared and he was covered in mud, needing his clothes washed.

Dena's body was found six days later in a field by a pond. That field was close to the grocery store and the boyfriend's home.

Confidential Witness 2 told investigators the uncle had once stormed into the home of the boyfriend's father, pushed the father against the wall and threatened him if he talked about the case.

Investigators say they're waiting on test results from DNA recently taken from the uncle.

"I think the end could potentially be near," said Huff.

These retired investigators are doing all this work on their own time and money. 

They say if anyone has information, now is the time to talk because people who knew something but kept it secret could also possibly face charges.