WASHINGTON (AP) — Hunter Biden was indicted Thursday on federal firearms charges, the latest and weightiest step yet in a long-running investigation into the president’s son.

Biden is accused of lying about his drug use when he bought a firearm in October 2018, a period when he has acknowledged struggling with addiction to crack cocaine, according to the indictment filed in federal court in Delaware by a special counsel overseeing the case.

President Joe Biden's son has also been under investigation for his business dealings. The special counsel has indicated that charges of failure to pay taxes on time could be filed in Washington or in California, where he lives.

The firearms indictment comes weeks after the collapse of a plea deal that would have averted a criminal trial as the 2024 election looms. Since then, the political pressure has only escalated as the House formally opened an impeachment inquiry into the Democratic president, seeking to tie the elder Biden to his son’s businesses and divert attention off former President Donald Trump’s own legal woes.

Over the yearslong probe, federal prosecutors have not indicated Joe Biden is connected. And so far, Republicans have unearthed no significant evidence of wrongdoing by the elder Biden, who as vice president spoke often to his son and stopped by a business dinner with his son’s associates. The White House maintains Joe Biden was not involved in his son’s business affairs.

The prosecutor who has long overseen the Hunter Biden investigation, Trump-appointed Delaware U.S. Attorney David Weiss, was elevated to special counsel last month, giving him broad authority to investigate and report out his findings.

The three-count indictment says Hunter Biden lied on a form required for every gun purchase when he bought a Colt Cobra Special at a Wilmington, Delaware, gun shop.

He's charged with two counts of making false statements by checking a box falsely saying he was not a user of or addicted to drugs and a third count for possessing the gun as a drug user.

Two counts are punishable by up to 10 years in prison while the third carries up to five years in prison, upon conviction.

Rep. James Comer, the lead Republican pursuing an impeachment inquiry into the president, called the indictment Thursday “a very small start.” But, he said in a statement, unless the Justice Department pursues the claims Republicans have put out regarding whether the president was involved in his son’s business dealings, “it will be clear President Biden’s DOJ is protecting Hunter Biden and the big guy.”

A felony gun charge against Hunter Biden, 53, had previously been part of a plea deal that also included guilty pleas to misdemeanor tax charges, but the agreement imploded during a court hearing in July when a judge raised questions about its unusual provisions.

The agreement would have spared him formal prosecution on the gun charge if he stayed out of trouble for two years. Defense attorneys have argued that part of the deal remains in place, including its immunity provisions against other potential charges.

The attorneys have indicated they would fight additional charges filed against him, but they did not immediately respond to a request for comment Thursday.

Prosecutors, though, maintain the agreement never took effect and is now invalid. They telegraphed new gun charges were coming earlier in a court filing earlier this month.

Charges related to gun possession by drug users are rare, especially when not in connection with other crimes. Of all the people sentenced for illegal gun possession in 2021, about 5% were charged due to drug use, according to U.S. Sentencing Commission data.

Most those cases are brought against people accused of some other crime as well, said Adam Winkler, a constitutional law professor and expert in gun policy at the University of California, Los Angeles School of Law. “It’s relatively rare to prosecute someone for being a substance abuser in possession of firearms, absent other criminal activity, or unusual circumstances,” he said.

A federal appeals court, meanwhile, recently found longstanding ban didn’t stand up to new standards for gun laws set by the Supreme Court.

Republicans had denounced the plea agreement as a “sweetheart deal.” It would have allowed Hunter Biden to serve probation rather than jail time after pleading guilty to failing to pay taxes in both 2017 and 2018.

His personal income during those two years totaled roughly $4 million, including business and consulting fees from a company he formed with the CEO of a Chinese business conglomerate and the Ukrainian energy company Burisma, prosecutors have said.

Congressional Republicans have continued their own investigations into the Justice Department's handling of the case as well as nearly every aspect of Hunter Biden’s business dealings, seeking to connect his financial affairs directly to his father. Republicans have obtained testimony about how Hunter Biden used the “Biden brand” to drum up work overseas, but they have not produced hard evidence of wrongdoing by the president.