BYU spokeswoman Carri Jenkins confirmed to The Tribune on Tuesday afternoon that Hadley has run afoul of the school's strict honor code, which forbids the use of alcohol, drugs and premarital sex, among other things.
She would not give details of the specific nature of Hadley's offense.
Jenkins said Hadley will serve a five-game suspension, meaning the soonest he could return will be for the Boise State game Oct. 25.
"During that time, Spencer will not be able to represent the university," Jenkins said, noting that Hadley will remain in school and work with Dean of Students Vernon Heperi to get the matter resolved.
Hadley's backup at buck linebacker is senior Tyler Beck, a 6-foot-2, 220-pounder who has had an injury riddled career at BYU.
Sophomore Manoa Pikula also could see some time replacing Hadley.
Hadley, from Connell, Wash., started in BYU's first two games and recorded 12 tackles and two pass breakups. The 6-1, 227-pound linebacker has started 16 games in his BYU career, and appeared in 39.