Updated

A former Iowa State University scientist has pleaded not guilty to charges alleging he falsified his research for an AIDS vaccine to secure millions of dollars in federal funding.

Dong-Pyou Han appeared in federal court in Des Moines on Tuesday and entered his pleas of not guilty to four counts of making false statements. Each count carries up to five years in prison and a $250,000 fine.

Han was released on bond and his trial was scheduled for Sept. 2. His attorney declined to comment afterward.

Prosecutors say before Han resigned last fall, he told university officials he had spiked samples of rabbit blood with human proteins to make it appear the vaccine was working.

The alleged misconduct was uncovered last year after Harvard University scientists discovered the spiked samples.