The FBI is investigating a West Palm Beach, Fla., eye doctor suspected of providing free trips and underage prostitutes to Sen. Bob Menendez.
Agents took potential evidence from the office of Dr. Salomen Melgen, a financial contributor to the New Jersey Democrat, late Tuesday night.
The probe is believed to be focusing on Melgen's finances as well as the allegations about Sen. Menendez's trips and contact with prostitutes.
Since 1998, Melgen has donated approximately $357,000 to various political candidates and committees despite having an outstanding IRS lien of $11.1 million for taxes owed for 2006 to 2009.
Melgen was first linked to the senator when two alleged prostitutes said they had relations with the New Jersey lawmaker at Melgen's Dominican Republic mansion.
Menendez has denied what he calls "fallacious allegations."
Meanwhile, Senate Majority Leader Harry Reid, D-Nev., remained tight-lipped about the case. He and other Democrats have suggested the allegations are nothing more than a right wing smear job.
"Always consider the source," The Miami Herald quoted Reid. "All anyone here has to look at is the source where this comes from."