Democratic New Jersey Sen. Robert Menendez has been indicted on corruption charges, and Palm Beach ophthalmologist Dr. Salomon Melgen is at the heart of the scandal.

In a 68-page indictment, Menendez is accused of accepting lavish gifts from Melgen, including private flights, vacations in the Dominican Republic, cash contributions, and more in return for political favors.

Those favors included fast-tracking visas for Melgen's foreign girlfriends and telling Medicare and Medicaid to look the other way when it came to Melgen's millions of dollars in overbillings.

Melgen, who owns four ophthalmology clinics in Palm Beach County, has been close friends with the senator for more than two decades after they first met at a Florida fundraiser in 1993, according to NJ.com.

Menendez has said in interviews that he talks to Melgen “weekly” and the two go to each other's family events.

This relationship has been under scrutiny by the Department of Justice for at least two years. But rumors of Menendez's being up to no good began in November 2012, when conservative news site The Daily Caller published a story accusing the prominent Democrat senator of having sex with prostitutes at Casa de Campo, a lavish villa in the Dominican Republic owned by Melgen.

It's not known if the prostitute accusations are true (Menendez, who is Cuban-American, accused the Cuban government of creating a smear campaign against him for being tough on the communist island), but it appears the Department of Justice began looking into the friendship at around this time. And the vacations at Casa de Campo are mentioned in the indictment.

The two-year probe says that, in addition to getting Melgen's girlfriends visas and trying to influence Medicare investigations, Menendez pressured the U.S. Department of State to influence the government of the Dominican Republic “to abide by Melgen's multi-million dollar foreign contract to provide exclusive cargo screening services in Dominican ports.”

Menendez also stopped the U.S. Customs and Border Protection from donating shipping container monitoring and surveillance equipment to the Dominican Republic because it might have threatened Melgen's cargo-screening business, which had a multi-million dollar contract with the Dominican government.

Those are all some pretty serious favors. And to get them, the DOJ says Melgen flew Menendez and his guests multiple times on private jets between New Jersey, South Florida, and the Dominican Republic. Menendez really liked the Casa de Campo, because he flew there at least nine times between 2006 and 2013.

Menendez, who has been divorced since 2005, also allowed Melgen to pay for a lovely trip to Paris for him and a girlfriend. The trip included first-class airfare and three nights at the five-star Park Hyatt Paris-Vendome, valued at $4,934.10.

But Melgen didn't just pay for Menendez's trips. In 2011, the Palm Beach eye doctor also gave $20,000 to Menendez's legal defense trust fund, which is appropriately named the Fund to Uphold the Constitution. A few months later, Melgen donated $20,000 more through his family members.

According to OpenSecrets, Melgen was the highest donor to the fund.

But that $40,000 was peanuts compared to what Melgen donated to Menendez's successful reelection campaign in 2012. Between May 2012 and October 2012, Melgen forked over $751,000 to "entities supporting Menendez's reelection effort."

Menendez and Melgen both maintain their innocence.

The entire 68-page document can be read below: