Police spokesman Anthony Guglielmi said Saturday there were no obvious signs of trauma or foul play and no suspicious factors surrounding Brown's death. He says it may take weeks before test results help determine the cause of death.
The 40-year-old Brown was found dead Friday at his home near Baltimore's Inner Harbor.
Brown was a 360-pound tackle who in 1999 was accidentally hit in the eye with a penalty flag and missed three seasons because of the damage it caused.
He played 10 seasons in the NFL -- four with the Cleveland Browns and six with the Ravens.