Cook returned to his home in Miami on Tuesday to be with his siblings and will miss the Vikings' daily COVID-19 tests, making him unavailable for the season finale, according to the source.
Cook's father, James, was 46 years old. The Vikings offered their condolences to Cook in a tweet Wednesday but have not announced the two-time Pro Bowler's status for Sunday.
The entire Vikings organization is thinking of Dalvin and his family following the passing of Dalvin's father, James Cook.— Minnesota Vikings (@Vikings) December 30, 2020
Quarterback Kirk Cousins and rookie wide receiver Justin Jefferson also expressed condolences Wednesday to Cook, who was selected as the 2020 recipient of the Korey Stringer Good Guy Award. The Minnesota chapter of the Pro Football Writers Association presents this honor each year to a Vikings player to recognize media cooperation and professionalism.
Cook leads the NFL in total yards from scrimmage (1,918) and scrimmage yards per game (137) and has scored 17 touchdowns this season. He is second in the league in rushing yards with 1,557, behind Tennessee Titans star Derrick Henry (1,777).
Cook joined Adrian Peterson and Robert Smith as the only players in Vikings history to rush for 1,500 yards in a season.
During his weekly Wednesday news conference, Vikings coach Mike Zimmer declined to say whether he has made a decision to rest starters in Week 17. Minnesota was eliminated from postseason contention with a Christmas Day loss to the New Orleans Saints.
Even if there were postseason implications, Cook would not have enough time to clear COVID-19 protocols in order to be allowed to play. The NFL has a six-day testing window for newly arriving players, a waiting period that applies to any interruption to the daily testing process.
Cook's absence will clinch a second consecutive league rushing title for Henry. The next-closest players after Cook on the league leaderboard are more than 700 yards behind Henry entering the final week. Henry will be the first repeat winner since LaDainian Tomlinson in 2006 and 2007.
Cook also will finish second in team history on the single-season list for yards from scrimmage, behind Peterson's 2,314 total yards in 2012, when he won the league MVP award. Peterson, with 18 scores in 2009, is the only Vikings player who has tallied more rushing touchdowns in one season.
The Associated Press contributed to this report.