GAINESVILLE, Fla. -

A devastated and inconsolable Carlos Aguilar said he can't wrap his mind around what is now the murder case involving his son, 18-year-old Christian.

"I don't have any more tears right now, but the pain is in my chest," he said. "I still feel my son is still alive in my heart..."

Police in Gainesville have filed a murder charge against Pedro Bravo, the 18-year-old suspect in a University of Florida student's disappearance, investigators announced Friday evening.

Bravo is accused of killing his childhood friend, 18-year-old Christian Aguilar. The teen's body hasn't been found. Aguilar disappeared Sept. 20.

Earlier Friday, police were asking for the public's help in determining where Bravo was over a 17-hour period, the time-frame Aguilar went missing. Investigators said they could not account for Bravo's whereabouts from 3 p.m. Sept. 20 to 8 a.m. Sept. 21.

Police said Bravo was at Best Buy at 3 p.m. Sept. 20, as seen on surveillance video with Aguilar, his childhood friend. Aguilar hasn't been seen since. Investigators said they also know where Bravo was in Gainesville at 8 a.m. the next day, but they didn't know where he was for the time in between.

Police released photos Friday of Bravo's 2004 Chevrolet Blazer (pictured below). 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 window.

Pedro 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.

More than 150 volunteers continued searching wooded areas Friday, eight days after Aguilar vanished. Police said their search efforts will continue, and they are encouraging residents to volunteer to help in the search.

Former classmates of both Bravo and Aguilar at Doral Academy Preparatory High School said they were raising money to help with the search. Organizations, including cheerleaders, have raised money to help Aguilar's family cover the expense of searching for him in Gainesville. Rodriguez said students have raised more than $12,000.

Aguilar's younger brother, Alexander, was looking through a scrapbook his family found in Christian's dorm room Friday morning that he was putting together with drawings and photos as a gift to his parents for their anniversary.

"They had no idea he was working on this. He kept it a surprise but he was always saying to me, ‘Do you think they would like this?’" he said.

Investigators said earlier this week that Bravo bought a shovel and duct tape several days before Aguilar went missing.

Bravo was in the Alachua County jail on a charge of depriving a victim of medical care when police filed the murder charge.

Carlos Aguilar, Christian's father, said he had been in contact with Bravo's father until Thursday, but he said Bravo's father is no longer answering or returning his calls.

Carlos Aguilar said his family was going to the jail Friday to try to talk to Bravo themselves. They tried to Thursday, but Bravo denied visitation.

"I don't think it's fair that a person is missing and the only person with information to find him is protected by the Fifth Amendment," Carlos said. "That's ridiculous. We need to be able to have the authorities talk to people like that."

For information on how to help in this case, check the Gainesville police Facebook page at www.facebook.com/gainesvillepolice.