Responding to a major case of research misconduct, federal prosecutors are taking a rare step by charging a scientist with fraud after he admitted falsifying data while researching an HIV vaccine.

Authorities say former Iowa State Univ. laboratory manager Dong-Pyou Han has confessed to manipulating data that helped his team get millions in grants and increased hopes of a major breakthrough in AIDS research.

Experts say the fraud was particularly brazen, and charges are rarely brought in part because less money is usually involved. The National Institutes of Health is reviewing the case’s impact on research it funds.

Han resigned from the university last fall. He was indicted last week and could face prison time if convicted. He’s free on bond but didn’t respond to a message seeking comment Tuesday.