The Gainesville Police Department's Mounted Patrol Unit and members of Texas EquuSearch joined the search for the missing University of Florida student Sunday afternoon.
Gainesville Police Cpl. Tracy Fundeburg said the effort is to exhaust all resources in the hunt for 18-year-old Christian Aguilar.
"We're doing what we call a grid search at this point. One person will stay on the main path or a little bit off of it," Cpl. Fundeburg said.
Cpl. Fundeburg described the advantages horses bring to a search in such a rural community.
"The obvious one is the height. You can look around you and see what you can see. We can see far and we can see into the taller grass," Cpl. Fundeburg said.
Christian Aguilar has been missing Sept. 20. Gainesville police charged Aguilar's friend and former Doral Academy classmate, Pedro Bravo, with his murder on Friday.
Bravo had previously been arrested for depriving a victim of medical treatment.
Investigators said Bravo confessed to beating Aguilar after they confronted him with new evidence, including the discovery of blood in Bravo's vehicle and Aguilar's backpack.
Authorities are testing the blood to see if it matches Aguilar's DNA. They said they found Aguilar's backpack inside a suitcase in Bravo's closet.
A police report revealed Bravo "stated that he had punched the victim (Christian Aguilar) in the face with his fist and forced him to get out of his vehicle during the argument. He attacked the victim and beat the victim for ten to fifteen minutes...The def (Bravo) stated that he was unconscious on top of the victim punching him until the victim lost consciousness. The def stated that the victim was barely breathing and not moving, lying on his back, partially in water, at the time that the def left him."
Bravo was denied bond Saturday and has been on suicide watch. He is being kept in the Alachua County jail's medical unit under close observation.
Gov. Rick Scott joined the massive search for Aguilar on Saturday, combing through wooded fields and parking lots.
On Friday, police asked for the public's help in determining where Bravo was over a 17-hour period, the time-frame Aguilar went missing. Investigators have been unable to account for Bravo's whereabouts on September 20 from about 3 p.m., when he was seen with Aguilar at an area Best Buy on surveillance video, to about 8 a.m. Friday.
Police released photos Friday of Bravo's 2004 Chevrolet Blazer. They noted the different front right wheel and tire, saying it is hopefully unique enough that someone remembers seeing the vehicle sometime within that time-frame.
Bravo's 2004 Chevrolet Blazer Bravo originally told police that he wrecked the Blazer about a week before Aguilar's disappearance, causing him to have to replace that rim, but police said none of that information could be confirmed.
Investigators were also asking for all business owners to check their outside surveillance video to see if that vehicle was seen on video. Police said they've reviewed a lot of video from Gainesville, but they were seeking areas outside of Gainesville due to the time window being so large.
They are encouraging property owners, residential or business, who may have lime rock roads on their property that are accessible to the general public to search those properties for any suspicious areas of ground that appear to have been disturbed.
"We had figured out some sort of a timeline for Christian on the last day he was seen. Now we're kind of switching gears to Pedro's timeline to figure out exactly where he was and see if we can kind of plug in some holes there," Gainesville police spokesman Ben Tobias said Friday morning.
Anyone who may have captured the SUV on video is asked to call police at 352-393-7670.