"I don't see a lot of evil there," Trump said of the circumstances surrounding the senator's passing. "I don't I know there's all sorts of conspiracy theories going along, and I don't think the FBI, I think the FBI is wasting their time if they're doing that."
Graham died in Washington, D.C., one day after returning from Kyiv, where he met with Ukrainian President Volodymyr Zelenskyy to discuss a new package of sanctions against Russia. A statement released by Graham's office on Sunday cited preliminary findings from the District of Columbia's Office of the Chief Medical Examiner, identifying the cause of death as an aortic dissection due to arteriosclerotic cardiovascular disease, though the official cause of death remains pending additional testing.
Trump also said multiple times in the Oval Office on Tuesday that Graham's father died of the same condition, though Politico reported in 2015 that his father actually died of a massive heart attack, which is different than an aortic dissection.
An aortic dissection is a life-threatening medical emergency in which a tear develops in the inner layer of the aorta — the body's largest artery, according to Mayo Clinic.
Fox News senior medical analyst Dr. Marc Siegel, who did not treat Graham, told Fox News Digital that it can "come on in minutes or days and may be hard to recognize."
In an interview with ABC News on Monday, Mehmet Oz, a board-certified cardiothoracic surgeon, echoed much of what Trump said about how Graham may have died.
Oz, also the administrator of the U.S. Centers for Medicare and Medicaid Services, used a paper towel roll as a prop to demonstrate what an aortic tear is.
"If the blood pressure is high or there is hardening of the arteries, which happens with age, you will actually tear this tube," said Oz, as he tore into the cardboard tube inside the paper towel roll.
"And as it tears, the blood, instead of being in the middle of the tube goes into the side of the tube, and there's no room to go there, so it starts to rip through these layers of the tube until ultimately there's no blood going where it's supposed to go," Oz said.
He continued: "So, you shut off blood to the heart, to the brain, the kidneys, to many parts of the body, and ultimately it just rips out. And when it rips out, it actually compresses the heart and that's called cardiac tamponade, and it's probably the reason we lost Sen. Graham."
Oz also said that when this happens to a person, there's not "a lot of time" to medically intervene and save them.
"The heart is pumping six liters a minute, so that's a lot of blood going in the wrong direction, spurting out of that tube, can take your life in many ways," Oz said.
Graham's sister, Darline Graham, was chosen by South Carolina Gov. Henry McMaster to serve out the rest of her brother's term in the Senate, which ends on Jan. 3, 2027. Darline Graham is scheduled to be sworn in at 2:30 p.m. on Tuesday.