Federal authorities have joined the investigation into the unexpected death of Sen. Lindsey Graham, with FBI Director Kash Patel confirming that the bureau is providing full support to local law enforcement as officials continue to examine the circumstances surrounding the longtime South Carolina senator’s passing.

Patel announced the FBI’s involvement in a statement posted Sunday on X, paying tribute to Graham’s years of public service. “Senator Lindsey Graham was a devoted public servant, a fierce defender of our nation, and a true patriot who dedicated his life to the people of South Carolina and the United States,” Patel wrote.

He also extended condolences to the senator’s family and associates while confirming the bureau’s role in the investigation. “Our prayers are with his family, loved ones, colleagues, and all those who knew him during this devastating time,” he added. “The FBI is assisting local authorities and has made every necessary resource available.”

Graham, 71, died Saturday evening after what his office described as a “brief and sudden illness.” News of his passing was released early Sunday.

In its statement, Graham’s office requested privacy for the family as they mourn. “Senator Graham’s family appreciates prayers at this time and asks for privacy during this incredibly difficult period,” the four-term senator’s office added.

Investigators from the FBI, the U.S. Capitol Police, and the Metropolitan Police Department are all participating in the inquiry as authorities work to determine whether there is any indication of foul play in the senator’s death.

According to police scanner recordings obtained by NBC News, emergency responders were dispatched to Graham’s Capitol Hill residence Saturday night following a report of a person suffering cardiac arrest.

Images obtained by NBC News showed paramedics transporting an individual from Graham’s home on a stretcher to a waiting ambulance, while numerous police vehicles and fire apparatus remained at the scene.

Only a day before his death, Graham had returned to Washington after traveling to Ukraine during the Senate’s recess. While overseas, he met Friday with Ukrainian President Volodymyr Zelensky.

A longtime advocate of strong American support for Ukraine, Graham had consistently backed the country’s war effort against Russia. During his visit, he also worked with a bipartisan group of senators and the White House to finalize language for new legislation aimed at imposing additional sanctions on Russia.

President Trump said Sunday that he had spoken with Graham shortly after the senator arrived back in Washington from Ukraine on Saturday evening.

Recalling their final conversation, Trump said Graham appeared somewhat fatigued after the overseas trip but gave no indication that anything was seriously wrong. “He sounded a little tired, but perfect. But a little bit tired, he had a right to be,” Trump told host Kristen Welker on NBC News’s “Meet the Press.”