A Department of Justice investigation turned up “corroborating evidence” that New Jersey U.S. Sen. Robert Menendez and a South Florida eye doctor, Salomon Melgen, used underage prostitutes in the Dominican Republic.

That claim is laid out in a 65-page motion filed Monday in the federal bribery case against Menendez and Melgen. The pair are accused of scheming to funnel hundreds of thousands of dollars from Melgen to Menendez in exchange for political favors.

The filing, which was published by U.S. News & World Report, responds in part to Menendez’s claim that the conspiracy investigation began only after accusations were made that he and Melgen were involved with underage prostitutes.

The Daily Caller first published allegations in 2012 that Menendez and Melgen had solicited prostitutes. In April, the DOJ indicted the pair, claiming that Menendez intervened to help several of Melgen’s girlfriends obtain U.S. visas. The Democrat also attempted to help Melgen with a Medicare fraud investigation, the government alleges.

In the filing, the DOJ attorneys assert that the corruption charges “are not tainted by unproven allegations” that they solicited underage prostitutes. The investigation was warranted given the “corroborating evidence.”

“Presented with specific, corroborated allegations that defendants Menendez and Melgen had sex with underage prostitutes in the Dominican Republic, the Government responsibly and dutifully investigated those serious allegations,” the government states.

“While those allegations have not resulted in any criminal charges, there can be no question that the Government has an obligation to take such allegations regarding potential harm to minors very seriously, regardless of who the alleged perpetrators may be,” the document reads.

In its filing, the DOJ’s attorneys take Menendez and his attorneys to task for characterizing the prostitution inquiry as relying on “such easily disprovable allegations about something that would hardly be a federal crime even had it been true.”

The government shot back: “As an initial matter, it is most certainly a federal crime to leave the country for the purpose of engaging in a commercial sex act with a minor, and the defendants’ suggestion to the contrary is unsettling,” adding that “the defendants’ dismissive treatment of these allegations is troubling.”

“Allegations of human trafficking and underage prostitution must be taken seriously and cannot be dismissed merely because the alleged perpetrator is a United States Senator.”

The filing states that eyewitnesses described a party at Melgen’s Casa de Campo resort in the Dominican Republican in which the eye doctor was present along with prostitutes. Menendez has stayed at Casa de Campo on numerous occasions. And according to the government, Menendez has also made “easily disprovable” statements about how many times he’s flown on Melgen’s private jet.

“Indeed, one of defendant Melgen’s pilots described ‘young girls’ who ‘look[ed] like escorts’ traveling at various times on defendant Melgen’s private jet,” the filing states.

The DOJ attorneys also refer to evidence that Melgen flew two women he met while they were performing at a South Florida “Gentlemen’s Club,” to Case de Campo. The day before he had paid one of the women $1,000 and the other $2,000.

“Some young women who received substantial sums of money from defendant Melgen were in the same place as defendant Menendez at the same time,” the filing adds.

Menendez’s office is denying the accusations.

“The motions [to dismiss that were filed earlier by Menendez] showed how the DOJ tried to make up for weak allegations about public corruption by soliciting allegations about sex,” Tricia Enright, Menendez’s communication director, told U.S. News & World Report. “The oppositions the DOJ filed [on Monday] continue that refrain, now with new salacious and baseless allegations, again having nothing to do with the actual charges in the case. While talk of prostitution may make for good headlines, it has absolutely nothing to do with this case.”

Govt Consolidated Opp to Def MTD – Misconduct – Filed

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