Washington (CNN) Sen. Robert Menendez pleaded not guilty on Thursday to 14 criminal counts against him, including eight counts of bribery in his dealings with Salomon Melgen, a Florida ophthalmologist.

They "don't know the difference between friendship and corruption and have chosen to twist my duties as a senator and my friendship into something that is improper," he said.

Despite the appearance of payment for services as alleged by the Justice Department, the two have been friends for decades, which Menendez allies say will make it challenging to successfully prosecute the two. As Menendez attorney Abbe David Lowell said during the Thursday press conference, prosecutors "have to prove beyond a reasonable doubt that a 20-year relationship between doctor Melgen and Senator Menendez was something else."

We've summarized the main takeaways from the Justice Department indictment so you can decide for yourself. One thing, at least, seems clear: Everybody should be so lucky to have a friend like Salomon Melgen.

THE GIRLFRIENDS

Girlfriend 1: A Brazilian national who worked as an actress, model and lawyer

Melgen offered to help fund graduate school for Girlfriend 1 at the University of Miami, and allegedly asked Menendez, who has been divorced since 2005, to help get her there.

According to the indictment, Menendez's office intervened on her behalf to help move her application for a student visa along in July 2008, but he had met her before her visa interview and knew her as Melgen's girlfriend.

A top Menendez adviser emailed the Deputy Assistant Secretary at Visa Services offering support for the woman's application, the day before her visa interview: "Sen. Menendez would like to advocate unconditionally for Dr. Melgen and encourage careful consideration of [Girlfriend 1]'s visa application."

The application was approved that day, and Melgen supported her education partially through a nonprofit he set up — called the Sal Melgen Foundation — with the self-described purpose of "help[ing] with the educational needs of disasvantages persons" and "assist[ing] with the economic educational needs of children in developing [sic] countires [sic] and the U.S."

Girlfriend 2: A Dominican national who worked as a model

Girlfriend 2 wanted to visit Melgen with her sister in 2008, when she was 22 years old and her sister was age 18.

Melgen initially wrote the U.S. embassy in the Dominican Republic asking for their visas to be approved and then contacted Menendez to help "move the letter along," according to an email between two Menendez staffers included in the indictment.

A Melgen aide told a Menendez staffer, per that email exchange, that the women wanted to visit around Christmas, to sightsee and tour around Palm Beach, and said they were "very good friends with Melgen." The Senate staffer said they "pressed for more info, but [the Melgen aide] wouldn't go beyond that" in elaborating on their relationship.

The indictment alleged that Menendez had met the woman in question, however, in 2008, and knew her as Melgen's girlfriend.

Staffers drafted a letter from Menendez to the embassy requesting approval for their applications: "They plan to visit someone I know well, Dr. Salomon Melgen, who is an eye doctor in Florida."

And the girlfriend asked for a copy of the letter from Melgen in a brief love letter:

"I write to remind you that you need to send me a copy of what Senator Bob Menendez's office sent you, which I need for the embassy," she wrote. "And also remember the bank thing please. Thank You. A Kiss."

Their applications for tourist visas were denied, because as the embassy employee explained in a memorandum, "neither is working. No solvency of their own. Not fully convinced of motives for travel." After repeated inquiries from Menendez's staff, their applications were approved after a second interview.

But at least one Menendez staffer raised a flag on the process. That staffer emailed another on their personal accounts referencing two people from the Dominican Republic who received visas.

"In my view, this is ONLY DUE to the fact that rm INTERVENED. I've told RM," the staffer wrote.

Girlfriend 3: A Ukrainian national who worked as a model and actress

Girlfriend number three was granted a visa to travel from Spain to Miami, Florida, to see Melgen after Menendez's office issued a letter, signed with the senator's name and advocating on her behalf, to visa officials.

The letter says Melgen "has extended an invitation to his good friend [Girlfriend 3] to undergo medical evaluation for plastic surgery as well as to visit with him within the U.S."

It also notes that the girlfriend was "the broadcast image for channel Tele 5 Spana and thus, a famous person in Spain," and so has ample ties to Spain that officials shouldn't be worried that she won't return home.

During her visit, Menendez met the girlfriend over dinner with Melgen at Azul, a restaurant in the Mandarin Hotel. The senator was introduced to the girlfriend, according to the indictment, as the man who helped her with her visa.

THE TRAVEL

From Punta Cana to Paris

The indictment outlines travel for seven trips Menendez took that Melgen paid for, typically on Melgen's private jet but at one point on a chartered private jet on which Menendez was the only passenger. The flights largely brought Menendez from New Jersey and Washington down to the Dominican Republic, where Melgen owned a Caribbean Villa (as it's described in the indictment).

One time, Melgen paid for a flight to Punta Cana for a wedding, where he also set Menendez and a guest up in a two-bedroom suite shared with Melgen and his wife, free of charge.

Another time, Melgen paid about $875 for a private car company to drive the senator from Hoboken, New Jersey, to and around New York City.

Melgen once used nearly 650,000 American Express rewards points to pay for a three-night stay in a luxury hotel in Paris for Menendez to meet up with his girlfriend. The room in the Park Hyatt Paris-Vendome cost nearly $1,540 per night, totaling $4,930 for the three-night stay, and Menendez described it in an email to Melgen as having a "king bed, work area with Internet, limestone bath with soaking tub and enclosed rain shower, [and] views of courtyard or streets."

"You call American Express Rewards and they will book it for you. It would need to be in my name," he told Melgen in an email at one point.

In 2013, after word of the federal investigation became public, Menendez paid back Melgen $58,000 for the 2010 plane trips calling his failure to properly disclose the flights an "oversight."

THE FUNDRAISING

"Don't worry. We will take care of it."

That was the response from a Melgen associate to a request from a Menendez aide for contributions to support the senator.

In an email sent in April 2012 to a Melgen aide, a Menendez staffer outlined requests for at least $60,000 in donations to entities benefitting Menendez. The staffer said he "humbly wanted to put a big ask" before Melgen, requesting the doctor and his family members contribute a total of $40,000 to the New Jersey Democratic State Committee Victory Federal Account, which would support Menendez and other New Jersey Democrats locked in re-election fights.

Melgen's personal assistant, identified in the indictment only as "Person A" responded: "Regarding your request ... don't worry. We will take care of it. Dr. Melgen will be calling you tomorrow to speak further."

On May 16, 2012, Melgen and his wife contributed $20,000 each to the New Jersey Democratic State Committee Victory Fund and the legal fund for Menendez, and Melgen's daughter and her husband contributed another $20,000 to the N.J. Democratic Party fund. Melgen appeared to reimburse his daughter with a $20,000 check issued from his ophthalmology practice that same day.

More than $750,000

That's the amount, according to the indictment, that Melgen gave — through his family and business — to entities supporting Menendez's re-election effort in 2012.

Of that, $143,500 went to New Jersey State and County Democratic Party entities. Melgen also contributed approximately $600,000 to Majority PAC, a super PAC backing Democratic Senate candidates and incumbents, in two contributions of $300,000. Both of which were earmarked for the New Jersey Senate race — in which Menendez was the only Democratic contender.

And Melgen also contributed $8,000 to an unnamed female senator -- who turned out to be Minnesota's Amy Klobuchar -- after Menendez and his staff asked the doctor directly to help return the fundraising favor to the senator, who had raised money for Menendez's reelection fight and was facing a primary challenge. Klobuchar announced she was returning the funds following the indictment.

THE BUSINESSES

"Who has the best juice at CMS and Dept of Health"?

That was something Menendez tried to determine when intervening on Melgen's behalf in a Medicare reimbursement dispute, according to an email he sent to a staffer that was included in the indictment — and the senator ended up speaking to the top officials at both the Centers for Medicare and Medicaid Services and the Department of Health and Human Services about the issue.

The indictment outlines a multi-year battle between Melgen and federal health officials over $8.98 million he was alleged to have over-billed Medicare for a drug he used in his ophthalmology practice.

Guidelines at the Federal Drug Administration and the Centers for Disease Control and Prevention called for each vial of the drug to be used for only one patient, to prevent the risk of contamination and the spread of infection, but Melgen allegedly used leftovers from single-use vials to treat additional patients — and then billed CMS for the full cost of a single vial for each dose of the drug he administered.

According to the indictment, Melgen and his associates repeatedly lobbied Menendez's office through emails, calls and meetings to intervene on his behalf in the dispute.

The senator ultimately secured conversations with both the acting administrator of CMS and the secretary of HHS, and was briefed by Melgen's team on the dispute before both meetings. He also got then-Senate Majority Leader Harry Reid's office involved in the dispute, according to multiple scheduling emails sent between the two offices.

During a July 2009 phone call with the head of CMS, the indictment alleges that Menendez "asserted that CMS' policy guidelines regarding single-use vials were vague and that a doctor in Florida was being treated unfairly as a result." When the administrator said they should "allow the case to take its course," Menendez, according to the indictment, told him "not to tell him about Melgen's appellate rights and abruptly ended the call."

The indictment alleges that, during his meeting with HHS Secretary Kathleen Sebelius , Menendez "advocated on behalf of Melgen's position in his Medicare billing dispute, focusing on Melgen's specific case and asserting that Melgen was being treated unfairly" — an assertion with which the secretary disagreed.

The meeting was "quite 'lively,'" according to an email from Melgen's lobbyist to two Menendez staffers after the meeting took place.

Menendez staffers also intervened in a trade dispute that would have allegedly affected Melgen's financial interests in the Dominican Republic. Emails included in the indictment show his staffers sought to prevent Customs and Border Patrol from donating screening equipment at ports that would've undermined Melgen's own screening business there.

THE TIMING

While there's no admission from either man in the indictment that any of the trips, contributions or perks Melgen paid for were expressly in exchange for Menendez's work on his behalf, in a number of instances the dates of the contributions coincide with actions taken by the senator's office that could have benefited Melgen.

The indictment notes that Menendez met with the top official at CMS about the dispute on June 7, six days after Melgen issued a $300,000 donation, through his business, to Majority PAC, earmarked to be used for the New Jersey Senate race.

On Oct. 19, 2012, Melgen emailed Menendez, a Menendez staffer and a Majority PAC fundraiser an update on his Medicare billing appeal. That was one week after Melgen issued, through his business, another $300,000 check to Majority PAC to be used for the New Jersey Senate race, and three $25,000 checks to New Jersey Democratic County organizations.

The Majority PAC fundraiser, also identified as a former Menendez staffer, replied to Melgen's email and promised to deliver the update to Menendez next time they saw the senator, later that week.

And on Jan. 11, 2013, Menendez directed his staffers via email to contact Customs and Border Patrol and try to prevent them from donating monitoring equipment for shipping ports that the indictment alleges would've impacted Melgen's financial interests. That was the day after Menendez, Melgen and another unnamed person golfed together at the private Banyan Golf Club in West Palm Beach, Florida, where Melgen paid for greens fees and the third person spent nearly $360 for dinner at a steakhouse.