Private investigator Bill Garcia helped lead the search, as well as a massive search on Saturday.
Garcia said efforts to find Amber Dubois have not turned up any new leads or information.
Dubois was last seen walking to Escondido High School the morning of Feb. 13.
Garcia said 90 volunteers focused on a specific part of Escondido Sunday.
Anyone with information about where Dubois may be is asked to call Escondido police at (760)839-4722.