Police say they have not been able to use security video in their investigation into the alleged sexual assault of a student outside Kelly Walsh High School on Monday.

That's because the surveillance footage is "unavailable," according to Casper Police Sgt. Mike Ogden.

"There are a lot of places that don't have surveillance, so we have to rely more on eyewitness testimony," Ogden told K2 Radio News on Wednesday.

Roughly 48 hours after the assault, police have no suspects and have named no persons of interest in the case.

The Natrona County School District has not responded to requests for comment on the matter. A phone call to Kelly Walsh High School was redirected to the office of the superintendent.

The alleged sexual assault was reported Monday afternoon by the Casper Police Department on their Facebook page.

Investigators say a female student reported the assault occurred at 11:45 a.m. that day, and she immediately notified the school.

The suspect was described as a white male standing six feet tall and weighing 180 pounds. He reportedly wore a gray t-shirt with faded jeans and had unshaven gray facial hair.

The suspect, police said, was last seen running north away from KWHS.

Casper police have stepped up their presence at area schools in the wake of the reported assault.

Anyone with information on the incident is asked to call the Casper Police Department at 235-8278.