(CNN) - Federal agents on Tuesday raided a South Florida office of Dr. Salomon Melgen, an eye doctor whose past issues with authorities had already entangled Sen. Robert Menendez.

With yellow crime tape strung up outside, men and women lugged box after box of materials from Melgen's West Palm Beach office into awaiting minivans. Both members of the federal Health and Human Services department and the Federal Bureau of Investigation took part in the search, which FBI Special Agent Michael Leverock said was the second at the same Melgen clinic - the other coming last January.