It's a complicated story with lots of moving parts. Given that, it's worth going through what we know and what we don't about Menendez, Melgen and their time spent in the DR together.
WHAT WE KNOW
* Melgen's office in Florida was raided by the FBI last week. According to the Miami Herald, "FBI agents were joined by an inspector from the U.S. Department of Health and Human Services, indicating the search-and-seizure raid has ties to a possible Medicare fraud inquiry." Melgen also owes the Internal Revenue Service more than $11 million in back taxes. Melgen's attorney has said he and his client haven't been informed why the doctor's office was raided.
* Menendez flew on Melgen's plane and stayed at Melgen's home in the Dominican Republic several times in 2010. In early January of this year, Menendez reimbursed Melgen $58,500 from his personal account for two flights in 2010. (A third flight by Menendez on Melgen's plane was paid for through the Democratic Senatorial Campaign Committee, which Menendez chaired at the time.) Menendez has chalked up the time between the flights and the reimbursement as an oversight; "I was in a big travel schedule in 2010," he said Monday. "I was the chair of the DSCC plus my own campaign getting ready for an election cycle." The Senate Ethics Committee is reportedly reviewing those allegations.
* Melgen was a major donor to Menendez and the DSCC during Menendez's time as chairman of the organization. Melgen also donated $700,000 to the Majority PAC, a Democratic super PAC that aimed to help elect (and re-elect) Democrats to the Senate, in 2012. That group spent almost $600,000 on Menendez's race, which he won last fall by almost 20 points.
* Melgen and Menendez have known each other for the better part of the last two decades. According to the New York Times, "they spent holidays together, often in the Dominican Republic, where Dr. Melgen has a home in Casa de Campo, a gated oceanfront resort where houses cost as much as $20 million and which has been home to some of the country’s richest residents, like Oscar de la Renta." Menendez has described Melgen as a "friend and political supporter."
* Menendez is forcefully denying a report from the Daily Caller, a conservative website, that he engaged in sex with prostitutes while in the DR. "Nobody can find them," he said of the alleged prostitutes Monday. "No one ever met them. No one ever talked to them." One of the women who supposedly slept with Menendez said Monday that she had never even met the New Jersey Senator.
WHAT WE DON'T KNOW
* Does the FBI raid on Melgen's office have anything to do with Menendez? The Miami Herald report suggests Medicare fraud, which, obviously would leave the Senator in the clear.
* Why did it take Menendez more than two years to pay back Melgen for the two flights to the Dominican Republic? Is "being busy" a good enough reason? And, does the timing of Menendez's payment -- less than a month before the raid on Melgen's office -- raise suspicions? Relatedly, does the Senate Ethics Committee go beyond simply reviewing the allegations and open a full investigation?
* Do any of Menendez's Senate colleagues -- particularly those in leadership -- turn on him? Senate Majority Leader Harry Reid (Nev.) gave Menendez a nice vote of confidence on Sunday, saying that the New Jersey Senator "did nothing wrong." Menendez's homestate colleague Frank Lautenberg has been less charitable but there has been no rush by other Democratic Senators to distance themselves from him. Any significant break in those ranks would be very problematic for Menendez.
* Does a very close look by the likes of the Washington Post, Miami Herald and New York Times turn up anything else incriminating or even questionable when it comes to the relationship between Menendez and Melgen? The piece of string that seems most likely to be harmful to Menendez is a port security contract in the Dominican that he pushed which would benefit Melgen.
HIstory suggests that this story will go one of two ways. Either the deep dig into Menendez by several major news organizations will turn up new information that forces him to explain himself at greater length and fuel the story or it won't. The next several weeks -- as news organizations flood the zone looking for new leads -- will be critical for Menendez.
If in a month's time, there's nothing new to report, he may well look back at this week as a big but ultimately inconsequential bump on his political road. If more comes out, however, Menendez could be in a fight for his political career.