NEW : Blood found in suspect 's vehicle , police say . Comment: Student 's backpack found at suspect 's home , police say . Christian Aguilar , 18 , was last seen September 20 in Gainesville , Florida . Pedro Bravo , also 18 , is charged with murder .
NEW : Blood found in suspect 's vehicle , police say . NEW : Student 's backpack found at suspect 's home , police say . Christian Aguilar , 18 , was last seen September 20 in Gainesville , Florida . Pedro Bravo , also 18 , is charged with murder .