Tim Miller founded the organization back in 2000, six years after his daughter, Laura, was kidnapped and killed.
"For many years I felt like this poor victim and wanted to throw in the towel and give up," Miller said. "I don't know what kept me going. I think it was that little voice I used to hear out there, 'Dad, don't quit.'"
Equusearch has been involved in nearly 1,500 cases.
Currently, volunteers are putting up fliers and scouring neighborhoods, looking for 27-year-old University of Houston student An Vinh Nguyen. He has been missing since March 31, and investigators believe he may be in Midtown or Montrose.
Volunteers are also looking for 26-year-old Karen Ramirez. She was last seen on March 24 in southeast Houston, and police believe a possible suspect in her disappearance may have escaped to South America.
Report a typo to the ABC13 staff