• Robert F. Kennedy Jr. lists on his June 30 financial disclosure report a brokerage account that held between $100,001 and $250,000 worth of bitcoin.
• Kennedy, who is running for president, told a crowd of crypto enthusiasts in May that he was not an investor in bitcoin.
• The filing does not say when the Kennedy family purchased bitcoin and how much they may have spent on their original bitcoin investment.
• Hours after publication of this story, the Kennedy campaign said that the bitcoin investment was his wife's. Later, the campaign then said it was indeed Kennedy's investment.

Robert F. Kennedy Jr., a Democratic candidate for president, stood at the world's biggest bitcoin conference in Miami in May and told the crowd, "I am not an investor and I am not here to give investment advice." Then he announced he would be accepting campaign donations in bitcoin.

What Kennedy didn't tell the crowd was that his family had invested in bitcoin recently, according to a financial disclosure form he filed June 30. On the twelfth page of the report, Kennedy lists a brokerage account that held between $100,001 and $250,000 worth of bitcoin. Hours after publication of this story, Kennedy's campaign manager, former Democratic Rep. Dennis Kucinich, told CNBC that the bitcoin purchase was made after the speech in Miami and before the June 30 filing deadline.

The situation could represent a conflict of interest if Kennedy were touting bitcoin on the campaign trail while his immediate family held the cryptocurrency, according to Virginia Canter, the chief ethics counsel for watchdog group Citizens for Responsibility and Ethics in Washington.

"There is no conflict here," Kucinich told CNBC in a follow-up interview.

Since the conference, Kennedy has continued to tout bitcoin.

In late June, he tweeted: "Bitcoin is not only a bulwark against totalitarianism and the manipulation of our money supply, it points the way toward a future in which government institutions are more transparent and more democratic." The tweet includes a video of part of his Miami speech where he describes how he would be pro-bitcoin as president.

The filing says the bitcoin holding made less than $201 in income but doesn't say when it was purchased. Nor does the filing say who purchased it or how much the family may have spent on their original investment. It also doesn't say whether they sold their bitcoin holding.

The bitcoin holding is listed under a section on the form that includes assets that can also belong to spouses and dependent children. It is intended to reflect holdings from the "preceding calendar year and current year to filing date," according to the Office of Government Ethics. Kennedy is married to "Curb Your Enthusiasm" star Cheryl Hines and has six children. Kennedy signed and filed the disclosure form to the Office of Government Ethics at the end of last month, according to the document.

After CNBC made multiple attempts to get a comment, the Kennedy campaign said hours after the publication of this story that "the investments were not his, but his wife's. He is not involved in her investment decisions." The campaign did not say for how long Hines held the bitcoin investment or when she purchased the asset.

Later Friday, however, a campaign representative sent a new statement, saying the bitcoin investment is indeed Kennedy's. "I was mistaken in my last communication. Mr. Kennedy does hold a bitcoin investment, but it came later. At the time of the bitcoin speech he had no cryptocurrency holdings," the representative said.

Before the Kennedy campaign commented, CREW's Canter said the ownership is certainly current as of June 30, when he filed his disclosure. "Under a traditional conflict of interest analysis, Hines' financial interests are imputed to him," Canter said.

"I'm really concerned that he's speaking at this conference, touting this investment to potential voters while the family has a history of owning bitcoin. It's like he could do the same thing for Procter and Gamble," she added. "There's no difference in my mind from a conflicts perspective."

After Kennedy's appearance in May at the Miami conference, CNBC inquired whether Kennedy had any crypto holdings. "Mr. Kennedy has no crypto holdings," a spokeswoman for the campaign said at the time.

Kennedy said at the conference that if he were to become president he would "make sure that your right to hold and use bitcoin is inviolable."

President Joe Biden's administration has waged an aggressive fight in regard to cryptocurrencies. Securities and Exchange Commission Chairman Gary Gensler told CNBC in June "we don't need more digital currency" after the SEC sued crypto exchange Coinbase for allegedly acting as an unregistered broker and exchange.

Bitcoin's price has seen an upswing recently, hitting a 13-month high Thursday, despite parts of the crypto industry seeing headwinds.

Kennedy's campaign has seized attention from several wealthy supporters, even as he remains far behind Biden in Democratic primary polls. A Quinnipiac survey from June shows Biden with 70% support among Democrats and Democratic-leaning voters, while Kennedy has 17%. Kennedy, 69, is the son of former Attorney General and U.S. Sen. Robert F. Kennedy and the nephew of former President John F. Kennedy, both of whom were assassinated in the 1960s.

Kennedy's pro-bitcoin stance has aligned him with several top tech investors, such as billionaire and bitcoin enthusiast Jack Dorsey, with several of them offering support for his presidential run. Others include David Sacks, Chamath Palihapitiya and Omeed Malik.

Kennedy, who has come under fire for spreading misinformation about vaccines at large, has a history of boosting bitcoin. His nonprofit, Children's Health Defense, or CHD, also has an interest in cryptocurrencies.

Its 2021 tax records show under the "investments" section that the group had crypto valued at over $78,000. A spokeswoman for CHD, which reportedly played a key role in pushing back on Covid vaccines and helping elevate Kennedy's profile before he began to run for president, previously told CNBC that the cryptocurrencies listed were not "investments" but, in fact, "donations." The CHD website shows that bitcoin is one of the cryptocurrencies accepted for donations toward the nonprofit group.

In April, before he started running for president, Kennedy tweeted what appeared to be an endorsement of bitcoin being a tool to avoid impacts from a struggling U.S. economy.

"Cryptocurrencies like Bitcoin give the public an escape route from the splatter zone when this bubble invariably bursts," Kennedy said.

In May, days before he took the stage at the Miami bitcoin conference, Kennedy tweeted: "Cryptocurrencies, led by bitcoin, along with other crypto technologies are a major innovation engine. It is a mistake for the U.S. government to hobble the industry and drive innovation elsewhere."

A day later he tweeted: "Bitcoin has been a lifesaver for people's movements around the world."

Note: This story was updated to include comments from Kennedy campaign manager Dennis Kucinich about the timeline of the Kennedy family's ownership of bitcoin.