 On January 21, 2008 investigators began sweeping the University of Nevada, Reno area in search of Denison.The Federal Bureau of Investigation (FBI) also joined in the search efforts.Investigators later learned that the male DNA found on the couch where Denison was sleeping the night when she disappeared was linked with at least 2 previous sexually motivated attacks in the same area, one on November 13 and a second one on December 16, 2007.