It has been reported that the Iranian researcher denied admission to the U.S. allegedly has ties to a volunteer militia that is linked to Iran's Revolutionary Guard.

Via Fox News:

Images aired on state television Thursday showing Mohsen Dehnavi's return confirmed that he was the same man who previously headed a student branch of volunteer paramilitary militia.

An earlier report in the semi-official Fars news agency said Dehnavi was appointed the head of the student Basij force at Iran's Sharif University in September 2007. The Basij is a volunteer militia that is linked to Iran's Revolutionary Guard.

Click here for the source.

And see via RFERL.org:

An Iranian medical researcher who was prevented from entering the United States to work at a Boston hospital is believed to have been an active member of the Basij force used in Iran as a tool of state repression.

Seyed Mohsen Dehnavi was the head of the Basiji at Tehran's Sharif University, former students at the university and activists claim.