Jason Richwine, the co-author of a controversial immigration study released this week by the Heritage Foundation, tells Post Politics that he has resigned his position with the organization.

"Yes, that's right," Richwine wrote in a brief e-mail. Heritage confirmed that he resigned.

The study written by Richwine and Robert Rector argued that the immigration reform bill would cost $6.3 trillion, but it was widely panned by conservative groups pushing for immigration reform as not accounting for the economic benefits of immigrants.

Complicating matters were a series of revelations about Richwine, including that he had written a doctoral thesis at Harvard University arguing that the United States should focus its immigration efforts on those with high IQs and that he had written for a Web site that describes itself as "nationalist."

Richwine's departure was first reported by Slate's Dave Weigel.