An extensive investigation of embattled Fannie Mae points to its former finance chief and controller as mainly responsible for the accounting failures at the mortgage giant now struggling to emerge from an $11 billion scandal, said a report released Thursday.

The report, by a team of investigators led by former Sen. Warren Rudman of New Hampshire, also found that former chairman and CEO Franklin Raines, while not sharing direct responsibility, contributed to a culture of arrogance at the government-sponsored company. The report, ordered by the company’s board, comes about 17 months after federal regulators discovered violations of accounting rules and earnings manipulation by the company to meet Wall Street targets.

Fannie Mae finances one of every five home-mortgage loans in the United States.