STILLWATER, Oklahoma - A Tulsa man has filed a lawsuit against Oklahoma State University over the death of his wife last year.

In the lawsuit, Ronald Mayfield says his wife Charlotte, fell backwards and hit her head on the steps while attending her grandson's high school football championship game at Boone Pickens Stadium in December 2011.

The lawsuit alleges that the university was negligent in its construction of the steps.

Mayfield says "the stairs in that section of the stadium were not clearly marked and did not have proper handrails."

Mayfield is seeking at least $75,000 in damages.

The university has not yet filed a response to the lawsuit.

Charlotte Mayfield's death came less than a week after a dozen fans were injured in the stadium while celebrating Oklahoma State's win over Oklahoma.

The Associated Press contributed to this story.