Terms of the deal were not available following Tuesday's announcement.
Brown is the third veteran receiver Indy has added this offseason. The Colts had already signed CFL veteran Duron Carter in February and Andre Johnson, the Texans' career receiving leader, in March. They also announced they would not re-sign fan favorite Reggie Wayne, who spent his entire career with Indy.
San Diego took Brown in the third round of the 2011 draft. He played in 37 games with the Chargers and Oakland Raiders, making 16 starts and catching 72 passes for 919 yards with three TDs. Brown missed all of 2012 with an ankle injury.
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