Senator Robert Menendez was indicted Wednesday on charges of political corruption for allegedly helping the business interests of a longtime friend in exchange for gifts and other kickbacks, according to a two-year federal investigation.

The Justice Department issued the charges after a federal grand jury in New Jersey, where Menendez is from, decided to indict the Democrat on five counts, including conspiracy to commit bribery and honest services fraud, The Wall Street Journal reported.

The charges- the first brought against a current U.S. senator since 2008- come after the Federal Bureau of Investigation launched a probe into the 61-year-old senator and his friend, Dr. Salomon Melgen.

Investigators believe Melgen, a Florida eye doctor, gave Menendez gifts including paid for trips to the Dominican Republic in 2010, according to CNN. Two years later, when the FBI's probe was announced, Menendez paid the doctor $58,000 for those two trips, claiming the failure to reveal the trips was an "oversight."

In 2012, Melgen donated $700,000 to help Menendez among other politicians. That same year, the senator urged U.S. Commerce and State officials to pressure the Dominican Republic to honor contracts with U.S. businesses, according to The Washington Post. The senator allegedly pushed the matter on behalf of Melgen, who was the chief investor of a company that had a port security contract in the D.R.

Menendez, a high-ranking Hispanic congressmen, recently admitted to receiving gifts from the doctor but said they were from a close friend he's known for the last 20 years.

He said he committed no crime and "always conducted myself appropriately and in accordance with the law," he told CNN before the indictment was issued. "And I'm not going anywhere."

The charges come at a trying time for Senate Democrats as they prepare to vote on the Obama administration's nominee to succeed Attorney General Eric Holder, the WSJ pointed out. The person that could take his place- Brooklyn U.S. Attorney Loretta Lynch- would oversee Menendez's prosecution, leaving a possibility for the senator to not give his vote.