Doral police ATV Doral police officers headed to Gainesville to assist in the search on Wednesday. Six officers left with K9s and all-terrain vehicles.

Miami-Dade County sent members of its Fire-Rescue K9's Urban Search and Rescue team and police canine team to help in the search on Thursday.

K9 officers from Sweetwater police have been helping with the search since the weekend.

"If he's buried or not, the dogs will find him," said one officer.

The search resumed Thursday morning. Investigators estimate that at least 10 square miles of wooded areas contained in the city of Gainesville have been searched by foot. They said other areas have been covered by helicopter, ATV, K9 and Mounted Patrol units.

Among the local, state and federal agencies assisting with the searches and investigation are the following:

FBI, Florida Department of Law Enforcement, U.S. Marshals Service, Alachua County Sheriff's Office, University of Florida Police Department, Miami Dade Fire Rescue, Miami Dade Police Department, Doral Police Department, Miramar Fire Rescue, Palm Beach County Sheriff's Office, Sweetwater Police Department, Brevard County Sheriff's Office, Medley Police Department, Florida Highway Patrol, Lafayette County Sheriff's Office, Cedar Key Police Department, Columbia County Sheriff's Office, Glades County Sheriff's Office, Putnam County Sheriff's Office, Levy County Sheriff's Office, Texas Equusearch, and Central Florida Search and Rescue.

On Wednesday afternoon, Aguilar's father asked anyone who knows what happened to his son to come forward.

Tips about what happened to Christian should be made by calling 352-393-7670.