The 30-year-old Brown has played for San Francisco (2007-2013) and Oakland (2014), and is one of the top players at the position still on the market. He previously visited the team in March.
Brown (5-foot-11, 190 pounds) landed on season-ending injured reserve with a broken foot last December. He has played in 114 career regular-season games (61 starts) and has 11 career interceptions and 59 passes defended.
The Patriots have two open spots on their 90-man roster, but it's uncertain if they'll make a move on Brown at this time.