RENO, Nev. -- The Reno Police Department has established a 24-hour tip line to gather information to assist in the investigation into the disappearance of 19-year-old Brianna Denison on Jan. 20.

On Monday evening, members of Denison's family made an appeal for her return and for anyone with information about her disappearance to call the tip line at 775-745-3521.

Information can also be called in to the Secret Witness Program at 775-322-4900 or the Reno Police Department Detective Division at 775-334-2115.

Officers have been canvassing the neighborhood and adjacent areas since Denison’s disappearance from a residence at 1395 Mackay Court, where she was spending the night with friends.

Searches of the area, including an extensive search of nearby Rancho San Rafael Park, have included using helicopters and police K-9 units.

Denison was reported missing Sunday by a friend with whom she was staying the night.

She is described as white, approximately 5 feet tall, with long dark brown hair and blue eyes and weighing about 98 pounds. She was last seen wearing pink sweatpants and a white tank-top shirt. A 24-inch tall brown stuffed bear with white and multi-colored balloons on its belly was discovered missing from the residence where she was staying.

Police are also hoping to speak with the driver of a beige or light brown Chevrolet or GMC suburban-style SUV, who provided a ride to the Mackay Court address for a friend of Denison's who lived there, to determine if he saw anything unusual.

He is described as being white, possibly of Latin descent, about 45 years of age, of medium stature and well-dressed. The vehicle was photographed by security cameras as it left the Sands Casino via the Arlington Street driveway.