Per ESPN's Josina Anderson, Mays has agreed to sign with the Vikings, thus, ending his career in Cincinnati for the time being while reuniting him with his former defensive coordinator, now head coach in Mike Zimmer.
The Bengals wanted to bring Mays back, but it looks as though he wanted to be with his former DC while also getting more playing time. The Vikings do have Harrison Smith at safety, but not much else, whereas Mays had little to no shot of playing in Cincinnati with Reggie Nelson, Shawn Williams and George Iloka ahead of him on the depth chart.
A former second-round pick in the 2010 NFL draft, Mays quickly went from starting safety for the San Francisco 49ers to trade bait -- with claims that he was a liability against the pass. Mays has played 50 games for the Bengals, including an eight-game stretch in 2013 where he played a linebacker/safety hybrid, filling in for the injured Emmanuel Lamur.
Mays later suffered a season-ending injury at the mid-season point that year. Other than that, he's been a special teams player, which is likely the role the Bengals will look to fill with Mays' absense.