DETROIT -- Detroit Lions running back Justin Jackson has retired from the NFL, abruptly ending his career after five seasons in the league.
The Lions announced Jackson's retirement Thursday, one day before their preseason opener, and signed veteran running back Benny Snell Jr.
Jackson, 27, was expected to compete for a reserve spot on the roster behind veteran newcomer David Montgomery and rookie Jahmyr Gibbs.
Jackson played in 16 games for the Lions last season after spending his first four years with the Los Angeles Chargers.