The Saints had signed Zenner just last week.
Zenner, 27, signed on with the Lions as an undrafted free agent out of South Dakota State back in 2015. He played out the final year of his three-year, $1.58 million contract but the Lions declined to tender him an offer as a restricted free agent and he tested the open market in 2017.
Detroit re-signed Zenner, but he was placed on injured reserve coming out of the preseason with a back injury. The Lions would later waive him with an injury settlement only to re-sign him in November.
Zenner returned to the Lions this past March but was cut loose at the end of August.
In 2018, Zenner appeared in eight games for the Lions and rushed for 265 yards on 55 carries (4.8 YPC) to go along with seven receptions for 56 yards receiving and three total touchdowns.