Federal prosecutors are considering charging Hunter Biden, the son of President Joe Biden, with three tax crimes and a gun-related charge, according to sources.

Two sources familiar with the matter told NBC News that the possible charges are two misdemeanor counts for failure to file taxes, a single felony count of tax evasion related to a business expense for one year of taxes, and a felony count related to a gun purchase.

Two senior law enforcement sources also told the outlet about the "growing frustration" inside the Federal Bureau of Investigation (FBI) as investigators finished most of their work on the case about a year ago. 

A senior law enforcement noted that the Internal Revenue Service (IRS) also finished its probe over a year ago.  The investigation into the president's son started in 2018.

It reportedly centered on his international business relationships, including any possible national security implications.

Sources said an examination of the income he earned from those ventures was also part of the investigation, as well as a false statement he allegedly made during the gun purchase.

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Hunter Biden Investigation

An attorney for a U.S. tax special agent said his client has information on how a criminal investigation into Hunter Biden has been hampered by "political considerations."

According to BBC, the lawyer for the unnamed agent said his client wanted to seek whistleblower protections from Congress to reveal what he knew as he claimed "preferential treatment and politics improperly infecting decisions" in the probe.

However, a White House official denied that Joe Biden had meddled in the probe into his son. Mark Lytle, the lawyer representing a career IRS Criminal Supervisory Special Agent who "has been overseeing the ongoing and sensitive investigation of a high profile, controversial subject since early 2020," wrote to a bipartisan group of lawmakers on Wednesday.

The lawyer said his client is prepared to "contradict sworn testimony to Congress by a senior political appointee." He noted that his client was ready to be questioned about what he knows and reveal "clear conflicts of interest" under "the proper legal protections."

However, Chris Clark, a lawyer for Hunter, told NBC News that the IRS agent appeared to have "committed a crime." Clark noted it was "a felony for an IRS agent to improperly disclose information about an ongoing tax investigation."

FBI Has Enough Evidence Against Hunter Biden

In October last year, the Washington Post reported that federal agents believed they had enough evidence to charge Hunter Biden with tax crimes and a false statement related to the gun purchase, claiming he was not addicted to or unlawfully using drugs.

The Guardian reported that the FBI was pressuring prosecutors to act on the case. Clark previously accused federal agents of illegally leaking information and asked Justice Department to investigate and prosecute the leak.

Hunter confirmed he was under probe for tax-related matters shortly after Joe Biden won the White House. The most examined issues were his business dealings and consultancies in Ukraine and China, including the payment he received from Ukrainian firm Burisma, worth $50,000 a month.

Aside from his business dealings, his laptop also became a controversial topic following the revelation of its contents after being left behind in a Delaware repair shop.

READ MORE: Inside Hunter Biden's Laptop: Data Confirmed to Be Created by Joe Biden's Son Himself as CBS Authenticated Its Contents

This article is owned by Latin Post.

Written by: Mary Webber

WATCH: IRS Whistleblower Claims Mishandling of Hunter Biden Probe - From ABC News