Carl Pelini resigned as coach at Florida Atlantic on Wednesday for what athletic director Patrick Chun called illegal drug use.
Chun said Pelini and defensive coordinator Pete Rekstis "tendered their resignations to me late this morning after I confronted both coaches with reports relating to their use of illegal drugs."
During a 19-minute news conference, Chun would not say when the use occurred. "I can't comment on specifics," he said, because it is a human resources matter.
Chun, who has been AD since July 2012, said "once the behavior was identified ... there was no debate" on whether the coaches would remain employed. FAU hired Chun away from Ohio State, where he had been an executive associate athletics director. He did not hire Pelini.
Chun also said there was no information "that suggests anyone other than these two individuals engaged in these activities."
In a statement released by the school, Pelini said, "I apologize for exercising poor judgment." He was not at the news conference.
Chun said Pelini will not be given a chance to address the team.
FAU becomes the fourth school with a coaching vacancy, joining USC, Connecticut and Miami (Ohio).
Pelini, 48, was just 20 games into his tenure at the Boca Raton-based school and finishes with a 5-15 mark, including a 2-6 record this season.
He is the older brother of Nebraska coach Bo Pelini, and was hired off the Huskers' staff after the 2011 season to replace Howard Schnellenberger, who had been the only coach in FAU history.
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Pelini's final game as coach turned out to be last Saturday's 45-10 loss at Auburn.
Offensive coordinator Brian Wright will serve as interim coach. Wright, 40, spent three seasons as the offensive coordinator at FCS member Montana State before being hired at FAU prior to last season.
This is FAU's first season in Conference USA after leaving the Sun Belt.
Chun said the hunt for a new coach already has begun. There should be no shortage of candidates. FAU sits right in the middle of prime recruiting ground in Palm Beach County, and there is no reason FAU (and FIU, located two hours south of FAU in Miami) can't annually contend for Conference USA football titles. FAU opened an on-campus stadium that seats 30,000 in 2011.