DETROIT — An insurance company refused to pay $300,000 in a head-on crash that killed a Watervliet man and his mother after a doctor came up with a key conclusion: Robert Krugman likely drifted out of his lane because of a heart attack.

A federal appeals court this week called the 2014 crash “tragic.” But it ruled in favor of Reliance Standard Life Insurance Co. because Krugman’s accidental death policy through his employer said no money would be paid if a heart attack contributed to an accidental death.

“I don’t begrudge them. They’re trying to enforce their policy,” Robert June, an attorney for Krugman’s sister, said Wednesday. “I don’t think they did anything nefarious or underhanded, even though I strongly disagree with their position.”

Krugman, 66, and his mother, Helen, also of Watervliet, were in a Honda Fit, traveling eastbound on Red Arrow Highway in Hartford Township. Peter Sinclair was westbound in a Ford Escape when the vehicles crashed head-on in the westbound lane. The Krugmans died but Sinclair survived.

A woman who lived about 70 feet away told police that she saw the crash and heard the Fit’s horn. But her statements were inconsistent, and police noted that a large tree obstructed the view from her kitchen window.

There’s no dispute that the crash killed the Krugmans. But an autopsy also found that the son had cardiovascular disease and 90 percent narrowing of a coronary artery.

Reliance Standard Life turned to Dr. Evan Matshes, who looked at the records and said there was “compelling evidence” that Krugman drifted from his lane because of an “acute and evolving” heart attack.

“More likely than not, Mr. Krugman became disoriented or incapacitated,” Matshes told the insurance company.

Judge Joan Larsen, writing for a three-judge panel at the 6th U.S. Circuit Court of Appeals, said Matshes offered a complete account.

“Krugman more likely than not crossed the center line in his Fit as a result of a heart attack,” she said.