A top Interior Department official is under scrutiny after it was revealed she knew oil and gas companies had avoided billions of dollars in payments two years earlier than she recently claimed. The case centers around the disclosure a bureaucratic error allowed offshore drilling companies to avoid paying royalties for extracting oil and gas from public waters. In September, Minerals Management Service Director Johnnie Burton said she was informed of the matter just last year. But Burton has now admitted she was told three years ago. An independent investigation says the government could have collected nearly $1 billion in just the last three years.