On Jan. 27, 11-year-old Gannon Stauch vanished from his Colorado Springs home after staying home sick from Grand Mountain School.

More than four weeks later, there is still no sign of the fifth-grader, and his family and law enforcement are still looking for answers.

The FBI, the National Center for Missing and Exploited Children and 15 other agencies have joined the search. As of Feb. 24, the El Paso County Sheriff’s Office has received 768 tips.

“It’s being worked 24 hours a day to bring Gannon home,” El Paso County Sheriff’s spokeswoman Jacqueline Kirby told PEOPLE. “Time is of the essence.”