The Major Case Squad of Greater St. Louis has turned the investigation into the disappearance of Denita Hedden back over to the Macoupin County Sheriff's Office.

In a statement released Tuesday, the Major Case Squad said a 12 day exhaustive investigative effort was conducted into the disappearance of the Royal Lakes woman, spanning seven consecutive days and covering large portions of southern Macoupin County.

According to the Major Case Squad, the endeavor has included more than 22,000 acres of rural terrain and 70 road miles. Numerous police, fire and specialized search teams have spent hundreds of man-hours in the interest of finding the 37-year-old. Major Case Squad investigators believe Hedden's disappearance involves foul play based on evidence recovered during the investigation. A person of interest has been identified, and the facts and circumstances surrounding the case have been provided to the office of Macoupin County State's Attorney Jennifer Watson.

Denita Hedden was last seen in the 700 block of Catalpa Avenue in Royal Lakes on January 25, at 11 p.m. She is a white female, standing five feet tall and weighing approximately 110 pounds.

Area property owners, farmers and residents are advised to report anything unusual that they may observe when traveling county and rural roadways. The search for Denita Hedden is expected to continue.