Prosecutors have introduced Hunter Biden's infamous laptop as evidence while questioning FBI agent Erika Jensen, their first witness.

Prosecutors asked Jensen about email messages found on the laptop and in Hunter Biden's iCloud account that appear to be about his drug use in 2018.

The government had said in pretrial court filings that it was planning to introduce materials on the laptop as evidence in the case.

The laptop has become a symbol of the legal and political controversy surrounding the president's son in recent years. Attorneys for Hunter Biden had previously attempted to preclude the laptop as evidence in the trial, arguing that they have "numerous reasons to believe the data had been altered and compromised before investigators obtained the electronic material."

But special counsel David Weiss argued in court filings that attorneys for Hunter Biden had not "provided any evidence or information that shows that his laptop contains false information," and the judge agreed to admit it as evidence.

Data from the laptop was purportedly obtained and later disseminated in 2019 by a Wilmington, Delaware, computer repairman after the laptop had been dropped off at his shop for repair.

With that context in mind, prosecutors did not rely on the laptop on its own; investigators said they cross-referenced every email, WhatsApp message, iMessage, and text message with Apple Inc. to establish the credibility of the data.

"Ultimately, in examining that laptop, were investigators able to confirm that it was Hunter Biden's laptop?" prosecutor Derek Hines asked Jensen.

"Yes," Jensen said.

"How?" Hines asked.

"Among other things, there was a serial number that's on the back of this laptop that matches the Apple subpoena records that they obtained in 2019, so it matches the registration of this particular device to the iCloud account at a particular date," Jensen said.

"So from the data from the laptop and the hard drive, did you -- what did you do next, or what did the FBI do next when assessing the addiction evidence?" Hines asked.

"So from the data that was extracted from both the iCloud back ups and this -- the laptop, investigators were able to go through largely WhatsApp messages, iMessages, and text messages, and found evidence of addiction within the messages," Jensen said.

Prosecutors also showed jurors an invoice for $85 from the computer repair shop where Hunter Biden dropped off the laptop for repair, which had been sent to an email address belonging to Hunter Biden.

"You said Apple Inc. provided that ... from the iCloud?" Hines asked.

"Yes," Jensen said.

In the first exhibits presented in the government's case, prosecutors played excerpts from the audiobook of Hunter Biden's 2021 memoir "Beautiful Things" -- in which jurors heard in his own words about some of the most personal low points of his yearslong addiction to crack cocaine.

FBI Special Agent Erika Jensen, the government's first witness, introduced about a dozen audio excerpts played out over an hour, as Hunter Biden's voice boomed over the courtroom's loudspeakers while his stepmother, first lady Jill Biden, and several other members of his family sat in attendance.

"I used my superpower of finding crack cocaine anytime, anywhere," Hunter Biden said of the year 2018 -- the same year he purchased the gun that prosecutors say he lied to get. The audio contained passages in which he spoke about the darkest and most dangerous moments of his addiction -- at one point doing cocaine in the bathroom while on a graduation trip with his daughter. .

Jill Biden and her daughter Ashley Biden sat shoulder-to-shoulder as the clips played out, at times leaning their heads against one another. At one point, as Hunter Biden's voice was heard describing a raucous 12-day bender in Los Angeles, Jill Biden lifted her left arm and draped it around Ashley's shoulders.

A person sitting with the family told ABC News they were both "fighting off tears."

Hunter Biden, for the most part, stared intently into the nearby monitor displaying the book's contents, at one point slightly nodding along as he reheard some of his most painful struggles. The jurors appeared largely engaged, with many taking notes and looking up at the screen to follow along.

Hunter Biden's attorney sought to cast doubt on the government's narrative during his opening statement, claiming that Hunter Biden was not actively using drugs at the time of his gun purchase and therefore did not "knowingly" lie on the federal form barring drug users from procuring a firearm.

"He did not knowingly violate these laws," attorney Abbe Lowell said, since there was "nothing on the form about the definition of a user."

Lowell told the jury that Hunter Biden was using alcohol at the time of the gun purchase, but that his drug use "did not start until later."

The attorney said that while Hunter Biden was in Delaware, where he purchased the gun, his behavior was "totally inconsistent" with how he presented it when he was on drugs.

"He spoke with his father, his uncle, his daughters," Lowell said, suggesting they would have noticed if he was "smoking crack every 15 minutes," as he described in his 2021 memoir, "Beautiful Things."

"There is no such thing as a high-functioning crack addict," Lowell said.

Lowell told the jury that Hunter Biden had entered a 12-day rehab program in California before returning to Delaware in the fall of 2018, just a week before the gun purchase, shepherded by his "Uncle Jimmy Biden," who Lowell suggested will testify at trial.

Lowell also pushed back on one of the government's key pieces of evidence -- a text Hunter sent to his then-romantic partner Halle Biden days after purchasing the gun, in which he claimed to be "on a car" smoking crack. Prosecutors said this was evidence that he was using drugs at the time, but Lowell said that, "in reality, he did not want to see Hallie."

As part of the defense, Lowell also appeared to shift some blame to the owners and employees at the gun store where Hunter Biden purchased the gun, saying they "wanted to make a sale."

Lowell claimed that Hunter Biden first purchased a BB gun and a knife at the store, and only purchased the gun after they approached him.

"Hunter wouldn't have known what a speedloader was," said Lowell, who also claimed the salesman never "took Hunter through" the form to ensure he understood it.

"How quickly does a person check through those boxes?" Lowell asked jurors.

Lowell also pushed back on allegations involving the gun pouch that was found with the firearm after Hallie Biden threw the gun it in a dumpster. Prosecutors allege that the pouch had cocaine residue on it, but Lowell said it was never checked for fingerprints and called into question its chain of custody.

"Hunter has never asked anyone to excuse his mistakes," Lowell said, before asking jurors to find him not guilty.

As Lowell delivered his opening statement, first lady Jill Biden, Hunter Biden's wife Melissa Cohen Biden, and his half-sister Ashley Biden sat largely stoic in the gallery. Hunter Biden kept his eyes on Lowell and his hands clasped. Jurors paid close attention, with several taking notes.

Government prosecutors told jurors in the trial's opening statements that they should make "no distinction for Hunter Biden or anybody else" as they weigh the gun case against the president's son.

Hunter Biden "chose to lie," prosecutor Derek Hines said, laying out the case that the defendant purchased a gun while knowing he was an addict and drug user.

Hines said Hunter Biden bought the firearm from a gun seller who will testify as a witness that the younger Biden filled out form 4473 -- consenting to a federal background check -- and certified that he understood the form. The prosecution said it will show Hunter Biden "bought a gun and lied during a background check."

The man who sold Hunter Biden the gun will testify that he watched the defendant fill out the form.

The gun was then "taken by someone concerned he had a gun. That person was Halle Biden," Hines said, referring to Hunter Biden's romantic partner at the time.

Halle Biden disposed of the gun in a dumpster, where it was retrieved by a man who will also be a witness called by the government.

"The police were called" when Halle Biden went to retrieve the gun, Hines said.

Hines, in his opening, said evidence will show that "Hunter Biden knew he was a drug user and a drug addict" when he filled out the form.

Hines cited Hunter Biden's memoir, "Beautiful Things," in which he wrote he had a "superpower of buying crack anywhere, anytime."

In text messages presented by the prosecution, Hunter Biden acknowledged, "I am an addict."

Hunter Biden spent the first day of his gun trial taking notes, reading documents placed in front of him by his attorneys, and often turning to catch a glimpse of the friends and family who came to court to support him.

At one point, he nodded along as a prospective juror spoke about her friend's overdose after addiction.

Jill Biden was seated behind Hunter Biden all day, and she watched attentively as some jurors told the court that they had such a skewed view of her family that they could not be impartial. The first lady did not appear to react in those moments, but at times her daughter Ashley Biden placed her hand on the first lady's back in support.

Hunter Biden's family members also appeared to be actively involved with his defense strategy -- at one point standing up and huddling with Hunter Biden's attorneys Abbe Lowell and David Kolansky after a sidebar.

When court was dismissed, Jill Biden gave Hunter Biden a hug and a kiss before he walked out hand-in-hand with his wife.