Hunter's investigation into doing business with China could embarrass Biden with his commitment to maintaining the independence of the judicial system.

After months of silence before the presidential election, US federal officials are now beginning to actively investigate the business dealings of Hunter Biden, son of President-elect Joe Biden.

The President's transfer group, elected on December 9, released a statement quoting Hunter as saying he had received notice that the US Prosecutor's Office in Delaware was investigating its tax matters.

This is not a new investigation to open at the time Biden is about to take office.

However, the investigation has been conducted silently over the past months, directed by the US Department of Justice to publicly ban activities that could affect the election, a source said.

During this period, federal prosecutors in Delaware, in collaboration with the Internal Revenue Service's (IRS) Criminal Investigation Team and the FBI, carried out public actions such as subpoena and questioning.

Investigators have repeatedly looked at Hunter's financial problems, including whether he and his associates violated tax laws and money laundering in overseas business transactions, especially China, according to the report.

Another source said some of the transactions involved people whom the FBI believes pose a risk of counterintelligence, a problem that often arises when dealing with Chinese businesses.

Investigators seem to focus on Hunter's China-related businesses.

After Vice President Joe Biden left the White House in 2017, Hunter managed to reach an agreement with CEFC China Energy to invest in US energy projects, according to documents released by Republicans.

One source familiar with the matter said at least one issue that kept investigators interested in the transaction was the 2.8-carat diamond Hunter received as a gift from Diep Gian Minh, the founder and former chairman.

In 2019, Hunter once told New Yorker magazine about the strong metal from the former president Diep.

"I know that's not a good idea. I just find this gift odd," said Hunter.

Hunter added that the deal with CEFC has failed and he doesn't see Diep as shady.

In an interview with the New Yorker, Hunter also talked about personal issues, like substance abuse and broken marriages.

Receiving such a gift could get Hunter into tax trouble, and he doesn't say how he solved the problem later.

Hunter Biden then briefly worked as a lawyer representing Patrick Ho, who runs an organization backed by CEFC and was convicted in 2018 for bribing millions of dollars to officials in Chad and Uganda, to

Hunter previously also participated in a joint venture with China that many officials in the Barack Obama administration are concerned about, according to New Yorker.

Information about the investigation was released just five days before the US electors voted Joe Biden as the next president.

"I won't say what they have to do or what to do. I won't say prosecute A, B or C," Biden told CNN's Jake Tapper in an interview last week.

"The person I choose to run the set will be someone who has the ability to independently make decisions about who to prosecute," Biden added.

Republicans in Congress will almost certainly embrace this investigation to further augment their arguments that Hunter's activities in China are indicative of Joe Biden's conflict of interest when

This will also be an issue that Biden's new attorney general will face during his Senate approval hearing.

President Donald Trump also faced a similar, but much more difficult, problem after taking office in 2017. Jeff Sessions, then attorney general, had to quickly withdraw from overseeing the investigation.

Sessions were part of President Trump's campaign team and he met with the then Russian ambassador, who became the target of an FBI investigation.

It is not clear whether Biden's nominations to the Ministry of Justice will get into such troubles.