The six-foot-two, 277-pound Alexander registered 23 tackles and five sacks in 23 regular-season games with Edmonton. He was originally selected in the fifth round, No. 35 overall, by the Toronto Argonauts in the 2011 CFL draft.
Saskatchewan selected Ogbongbemiga in the third round of the 2016 draft.
* The club also announced it released Canadian kicker Johnny Mark.