WATCH: Trump says FBI is 'wasting their time' if agency is investigating Sen. Graham's death

President Donald Trump said he doesn't know why the FBI is looking into Sen. Lindsey Graham's death.

Watch the clip in the video player above.

The president said the late South Carolina senator had "a problem" and that what ultimately took his life "is actually something that's very hard to detect."

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A preliminary medical examiner's report said Graham suffered a tear in his aorta.

Trump said he's watched medical reports about Graham's case and had White House doctors explain to him what happened. "And this is something that is very almost undetectable," Trump said, adding that there's not much that can be done about a torn aorta.

"So I don't see a lot of evil there. 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 it," Trump said of an investigation.

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