PEMBROKE PARK, Fla. -

Pedro Bravo poisoned and suffocated University of Florida student Christian Aguilar, according to a grand jury indictment.

An indictment released Thursday didn't specify how Bravo poisoned Aguilar. It changed the original indictment and added new charges.

Prosecutors tell the Gainesville Sun traces of an unnamed, over the counter drug were found in a container inside Pedro Bravo's car. A drug that, in excessive quantities, could have rendered Christian Aguilar defenseless against Bravo.

Aguilar, 18, and Bravo, 19, went to school together at Doral Academy. Aguilar was last seen Sept. 20. Bravo first told police he beat Aguilar and left him near a field on the UF campus, but police couldn't find the body.

But prosecutors told reporters Bravo had no bruises on hands, no cuts, no swelling, nothing to indicate he hit anybody. That's why they believe Aguilar was suffocated, before his body was buried in a shallow grave in a remote area an hour west of Gainesville.

The grand jury has charged Bravo with murder, kidnapping, poisoning and tampering with evidence, providing false reports to law enforcement authorities, providing false information to law enforcement, and improper transportation of a dead human body. Detectives still haven't found the shovel and roll of duct tape they say Bravo purchased days before Aguilar was reported missing.

Christian Aguilar's body was discovered by hunters in the deep woods of Levy County on October 17, nearly a month after he disappeared.

The indictment doesn't mention a motive but prosecutors believe Bravo was angry because Aguilar was dating his former high school girlfriend.

Bravo is being held on no bond.