Police searching for a missing University of Florida student announced Wednesday that the teen arrested on charges related to the case bought a shovel (similar to the one pictured below) and duct tape several days before 18-year-old Christian Aguilar's disappearance.

Pedro A. Bravo, 18 -- a childhood friend of Aguilar -- was arrested Monday afternoon on third-degree felony charges of depriving a victim of a crime of medical treatment. He was ordered held on $100,000 bail.

Aguilar was last seen Thursday afternoon in the parking lot of Best Buy on Southwest Archer Road. Police say he and Bravo were fighting over a girl. (Surveillance photo of Aguilar and Bravo at Best Buy below.)

Police said Shovel bought by Pedro Bravo Wednesday the last known activity for Aguilar's cellphone was at 8:14 p.m. Thursday when it was powered off. There was no location attached to where it was powered off, and the cellphone has not been found, police said.

Investigators said they are also still looking for the shovel Bravo bought.

"It's a small shovel, it's not a giant shovel, but I can only speculate what it can be used for," Gainesville police spokesman Ben Tobias said.

"All the crying that you see over there, because I told them (Aguilar's family) we have to start thinking the worst," an emotional Carlos Aguilar, Christian's father, said at a news conference Wednesday morning. "That evidence is indicating that it's a possibility that my son -- that this guy planned this one and he's not telling the entire truth."

Hope that Christian Aguilar is still alive is dwindling as each day passes, but family and friends aren't giving up yet.

"The concern is very obvious, and the family is already aware of this information, and it changes the way we search somewhat," Tobias said. "With any missing persons case, with every day that goes forward, the likelihood and the odds just get less and less."

The photo of Aguilar and Bravo entering Best Buy was a trip for Aguilar to purchase Kanye West's newest CD, police said. They said they have recovered the jewel case and wrapping, but they are looking for the CD itself during their searches.

Police have said Bravo has given them three versions of what happened the day Aguilar disappeared. In one version, the two just talked. In another, he hit Aguilar and then left. The other version has Bravo beating Aguilar unconscious before leaving him in a parking lot off 13th Street.

Best Buy surveillance Aguilar's father says Bravo was jealous of his son's acceptance at UF, while Bravo was going to Santa Fe Community College. Both teens graduated from a private school in Miami last year.

Tobias says Bravo took investigators to several locations where he said he had been with Aguilar. Nothing was found at those locations.

Aguilar's family and Bravo's parents were at Tuesday's first-appearance hearing, where Aguilar's mom begged Bravo to speak up.

"One of the things that I thought was important was that he saw my family there," Carlos Aguilar said. "The first phone call that I made it was to Pedro's father, OK, and we keep a line of communication because my only desire is that he tells me where my son is at and that we can narrow down the look for my son."

IMAGES: Family, friends of missing UF student search woods|Candlelight vigil

While Bravo was initially called a person of interest, Tobias said Tuesday that Gainesville police do not see any difference between person of interest and suspect.

On Tuesday morning, police set up a command post for search efforts at Forest Park at the intersection of S.W. 43rd Street and S.W. 20th Avenue. Police say they have executed several search warrants and were using cellphone data and other leads to determine what happened to Aguilar.

Pedro Bravo Bravo (pictured, right) was previously being held under the state's Baker Act after making comments to police about wanting to harm himself. Police say Bravo has hired a lawyer, so investigators aren't able to talk directly to him.

Police say Aguilar may be disoriented or seriously injured and may not be able to seek help. Aguilar was last seen wearing a blue-gray hoodie and light-colored jeans.