Oklahoma athletic compliance officer Larry Naifeh interviewed players and athletic department personnel about Howard Schnellenberger's personal habits in the days before the coach abruptly resigned, the Tulsa World reported Friday.
The newspaper said two high level sources who spoke on condition of anonymity confirmed the interviews, which included questions about the consumption of alcohol on university property and while representing the school in official business.
Schnellenberger resigned Monday after a year and two days as coach of the Sooners.
The newspaper said Naifeh reportedly spoke with a player who said he smelled alcohol on Schnellenberger's breath during a university-related function. It said Athletic Director Donnie Duncan confronted Schnellenberger about the accusation Sunday.
Joe Novak returned to Northern Illinois as head coach after 22 seasons as a defensive assistant at several schools.
Novak was defensive coordinator at Northern Illinois from 1980 to 1983. He was most recently at Indiana and has worked at Miami of Ohio and Illinois.
Novak replaces Charlie Sadler, who was 18-37 in five seasons, 3-8 in 1995.