The U.S. Justice Department has launched a probe into allegations that up to 80 complaints of sexual assault over three years were not investigated thoroughly in a college town in Montana.

The investigation will look into sexual assault investigations at the University of Montana at Missoula, the Missoula Police Department and Missoula County Attorney’s Office.

“Late last year, the Department became aware of serious concerns that alleged sexual assaults of women, including but not limited to students at the University of Montana, were not being investigated in a prompt and adequate fashion,” Assistant Attorney General Thomas E. Perez of the Justice Department’s civil rights division said at news conference Tuesday.

“Our primary focus is not the number of reported allegations of sexual assault; rather, our focus is on the response,” he added.

Fred Van Valkenburg, Missoula County chief prosecutor, vehemently defended his office and the police officers involved in the investigations.

“We adamantly deny that we have done any such thing and we are deeply disturbed with the allegation that we have done so,” he said, according to the Missoulian newspaper. “While we have no choice, given the heavy hand of the federal government, but to cooperate with this investigation… I think it is an overreach by the federal government.”

The 80 reported cases occurred in a three-year period. A rash of sexual assault complaints at the University of Montana are also under investigation. At least two of the allegations are said to involve football players on the University of Montana Grizzlies football team.

Missoula, a city of about 67,000 people in western Montana, is tied to the school in many ways. The University of Montana is the top employer in the city.

In December, the University of Montana initiated its own investigation after allegations of a female being gang-raped and possibly drugged by other students. The university hired Montana Supreme Court Justice Diane Barz to investigate and she looked into nine alleged sexual assaults from September 2010 through December.

Barz wrote in her report that the university has “a problem of sexual assault on and off campus.”

Perez said there has been at least 11 allegations of sexual assault involving students in the last 18 months.

“As to the University, we are investigating whether it responds promptly and effectively to allegations of sexual assault and harassment on campus and has taken the necessary steps to combat sexual violence,” Perez said.

At least two of the allegations have involved players at the University of Montana Grizzlies football team, the Missoulian reported.

After the allegations last year, the school’s football coach and athletic director were dismissed, the paper reported.