Vince Foster’s sister on Thursday condemned Donald Trump for bringing up a discredited conspiracy theory regarding her brother’s suicide, calling the GOP nominee’s remarks “beyond contempt.”

Trump in a recent interview with The Washington Post referenced the widely debunked theory that Foster, a former White House aide to President Bill Clinton, was actually murdered. Trump called circumstances of Foster’s 1993 death “very fishy.”

“In this interview, Trump cynically, crassly and recklessly insinuated that my brother, Vincent W. Foster Jr., may have been murdered because ‘he had intimate knowledge of what was going on’ and that Hillary Clinton may have somehow played a role in Vince’s death,” Foster’s sister, Sheila Foster Anthony, said in an op-ed published in The Post Thursday.

Close video Trump reignites Clinton conspiracy theory Donald Trump has attacked Bill Clinton as a predator and Hillary Clinton as an enabler; now he’s jumping on the Vince Foster conspiracy bandwagon. What does Trump gain from these attacks? Donald Trump has attacked Bill Clinton as a predator and Hillary Clinton as an enabler; now he’s jumping on the Vince Foster conspiracy bandwagon. What does Trump gain from these attacks? share tweet email Embed

“How wrong. How irresponsible. How cruel,” she wrote.

Five investigations — by the FBI, the Department of Justice, Congress, the U.S. Park Police and two independent investigators — concluded that Foster took his own life after a struggle with clinical depression.

Anthony said in the op-ed that her brother called her a few days before he died and said he was battling depression. She gave him the names of three psychiatrists; a list that was later found in his wallet.

“I did not see a suicide coming, yet when I was told that Vince was dead I knew that he had killed himself,” Anthony said in the op-ed. “Never for a minute have I doubted that was what happened.”

She denounced Trump for giving legitimacy to conspiracy theories about Foster’s death by calling the theories “very serious” — even if Trump claimed he was just repeating the questions of others.

“This is scurrilous enough coming from right-wing political operatives who have peddled conspiracy theories about Vince’s death for more than two decades,” Anthony wrote. “How could this be coming from the presumptive Republican nominee for president?”

Anthony said she wrote the op-ed because The Post sought her reaction. She said she has donated to Hillary Clinton’s campaign, but has not had contact with anyone at the campaign about the decision to speak out.

“For Trump to raise these theories again for political advantage is wrong. I cannot let such craven behavior pass without a response,” she wrote.

This article originally appeared on NBCNews.com.