The suspect raped a woman near UCSD in November 2008 and forced his way into homes in Carmel Valley, Tierrasanta and the College area.
Police released a sketch of the suspect. He is believed to be white or Hispanic, in his 20s or 30s, about 5 feet 8, with a thin to medium build.
Authorities said all the victims have been Asian women and all were held at knifepoint.
Anyone with information is asked to call Crime Stoppers at (888)580-8477.