DENVER -- For the first time since a sexual assault scandal broke within the Air Force Academy, civilian authorities are investigating an allegation, a prosecutor said Saturday.

Dan May, assistant El Paso County district attorney, declined to release any details about the allegation.

The district attorney has concurrent jurisdiction at the academy, and the sheriff's department also has an agreement allowing it to investigate cases there, May said.

The Air Force has two investigations under way at the academy into allegations that female cadets were reprimanded or ostracized for reporting sexual assaults. The Defense Department's Inspector General plans to start its own investigation next week.

The Air Force says there have been at least 56 reports of sexual assaults of female cadets over the last decade.

Critics of the academy have said the only way to find the truth is to have a civilian investigation.

The scandal, which has been discussed during U.S. Senate hearings, likely will be the subject of hearings in the House as well. Both Democrats and Republicans have demanded action, and U.S. Rep. Tom Tancredo, R-Colo., has called for the dismissal of top academy commanders.

May said many factors will have to be taken into account when a decision is made on whether to prosecute anyone. They include a 10-year Colorado statute of limitations on sex crimes, whether evidence is still available, and the fact that witnesses could be spread all over the globe.