The former Cleveland Browns and New York Jets coach will work on Jim Harbaugh's staff for the two-time reigning NFC West winners, the person said, speaking on condition of anonymity because the team had made no formal announcement.
With a defensive expertise and experience as an assistant on that side of the ball, Mangini might help game plan for opposing defenses in the new role. San Francisco lost 34-31 in the Super Bowl to the Baltimore Ravens in February after missing scoring chances in the waning moments.
Quarterback Colin Kaepernick's second-half rally fell short and the Niners were denied a sixth championship. Kaepernick missed three chances from the 5, throwing three straight incomplete passes intended for Michael Crabtree, who got tangled up with a defender on the final play but no holding was called — Harbaugh screamed from the sideline and signaled for a penalty.
Kaepernick's off-balance throw under pressure on fourth down sailed through the end zone.
The 42-year-old Mangini had been working as an analyst with ESPN since August 2011, after being fired by the Browns in January that year following a pair of 5-11 seasons — the second time he lost a head coaching job in just more than two years. He went 10-22 in two years for Cleveland after three seasons in New York, where he led the Jets to the playoffs in his first year after replacing Herm Edwards in 2006.
Mangini then went 4-12 in 2007 and was fired after the team faded late the following year, finished 9-7 and missed the playoffs with Brett Favre as quarterback.
Mangini also has served as an assistant for the Jets, Browns, New England Patriots and Ravens, so getting back into coaching certainly was a strong possibility with it being such a part of him.