TULSA, Oklahoma - The Tulsa County Cold Case Squad is stepping up its efforts to find the person who murdered 16-year-old Dena Dean in 1998.

Sources told News On 6, investigators are now looking for and want to talk to three potential witnesses.

Sources say Dowilla Converse lived about a mile from where Dena's body was found. Investigators believe she has information specific to the case and are asking her to come forward.

They are also looking for a woman named Samantha.

They say about a year and a half ago, she was drinking at the It'll Do Lounge and told someone she knew about the suspects and named names.

 Investigators don't know her last name but believe she lives in the West Tulsa area.

Finally, they want to talk to a security guard who worked at a bingo parlor in the Town West Shopping Center the night Dean disappeared, June 6, 1998.

Investigators believe he saw the suspect vehicle fleeing the parking lot after Dena was kidnapped.

Dean went to the Town West Shopping Center that night to meet a friend. Her car was there but she was not.

Searchers found her body six days later, less than three miles from the shopping center.

If anyone knows where these three witnesses are, please call Crime Stoppers at 918-596-COPS.