NEW YORK (AP) — Moments after Luigi Mangione was handcuffed at a Pennsylvania McDonald’s, a police officer searching his backpack found a loaded gun magazine wrapped in a pair of underwear.

The discovery, recounted in court Monday as Mangione fights to keep evidence out of his New York murder case, convinced police in Altoona, Pennsylvania, that he was the man wanted in the killing of UnitedHealthcare CEO Brian Thompson in Manhattan five days earlier.

“It's him, dude. It's him, 100%,” an officer was heard saying on body-worn camera video from Mangione’s Dec. 9, 2024 arrest, punctuating the remark with expletives as the officer combing the bag, Christy Wasser, held up the magazine.

Wasser, a 19-year Altoona police veteran, testified on the fourth day of a pretrial hearing as Mangione sought to bar prosecutors from using the magazine and other evidence against him, including a 9 mm handgun and a notebook found during a subsequent bag search.

The testimony shed light on the critical minutes after Mangione was spotted at the McDonald’s and the sometimes unusual steps police officers took in collecting evidence critical to tying him to the crime.

Why the defense says the evidence shouldn't be used at trial

Mangione’s lawyers argue the items should be excluded because police didn’t have a search warrant and lacked the grounds to justify a warrantless search. Prosecutors contend the search was legal and that police eventually obtained a warrant.

Wasser, testifying in full uniform, said Altoona police protocols require promptly searching a suspect’s property at the time of an arrest, in part for dangerous items.

On body-worn camera video played in court, Wasser was heard saying she wanted to check the bag for bombs before removing it from the McDonald’s. Despite that concern, she acknowledged in her testimony Monday that police never cleared the restaurant of customers or employees.

Mangione, 27, has pleaded not guilty to state and federal murder charges. He appeared in good health on Monday, pumping his fist for photographers and chatting with his lawyers as testimony resumed.

The hearing, which was postponed Friday because of Mangione’s apparent illness, applies only to the state case. His lawyers are making a similar push to exclude the evidence from his federal case, where prosecutors are seeking the death penalty.

Why prosecutors say jurors should be able to see the evidence

Prosecutors have said the handgun found in the backpack matches the firearm used in the killing and that writings in the notebook showed Mangione’s disdain for health insurers and ideas about killing a CEO at an investor conference.

Thompson, 50, was killed as he walked to a Manhattan hotel for his company’s investor conference on Dec. 4, 2024. Surveillance video showed a masked gunman shooting him from behind. Police have said “delay,” “deny” and “depose” were written on the ammunition, mimicking a phrase used to describe how insurers avoid paying claims.

Mangione was arrested in Altoona, about 230 miles (370 kilometers) west of Manhattan, after police there received a 911 call about a McDonald’s customer resembling the suspect.

Wasser testified that she went to the McDonald’s on her own to assist another officer, Joseph Detwiler. Before that, she said, she had seen some coverage of Thompson’s killing on Fox News, including the surveillance video of the shooting and images of the suspected shooter.

Wasser began searching Mangione’s bag as officers took him into custody on initial charges of forgery and false identification, after he acknowledged giving them a bogus driving license, police said. The same fake name was used by the alleged gunman used at a Manhattan hostel days before the shooting.

By then, a handcuffed Mangione had been informed of his right to remain silent — and invoked it — when asked if there was anything in the bag that officers should be concerned about.

Wasser told another officer she wanted to check the bag for a bomb before leaving the McDonald’s because she didn’t want to repeat an incident in which another Altoona officer had inadvertently brought a bomb to the police station.

What did police find in Mangione's bag?

“Did you call the bomb squad?” Mangione lawyer Karen Friedman Agnifilo asked.

“No. I didn’t find a bomb yet,” Wasser responded.

According to body-worn camera video, the first few items Wasser found were innocuous: a hoagie, a loaf of bread and a smaller bag containing a passport, cellphone and computer chip.

Then she pulled out a gray pair of underwear, unwrapping them to reveal the magazine.

Satisfied there was no bomb, she suspended her search and placed some of the items back in the bag. Some evidence, including Mangione’s laptop computer, was transported to the police station in a brown paper McDonald’s takeout bag, body-worn camera video showed.

Wasser resumed her search after an 11-minute drive to the police station and almost immediately found the gun and silencer — the latter discovery prompting her to laugh and exclaim “nice,” according to body-worn camera footage. Wasser said the gun was in a side pocket that she hadn't searched at McDonald’s. Later, while cataloging everything in the bag in what's known as an inventory search, she found the notebook.

“Isn't it awesome?” Wasser said at one point during the search, according to the body-worn camera video.

Asked to explain, she told Friedman Agnifilo on Monday that she was proud of her police department’s work in helping to capture Thompson’s suspected killer.

A Blair County, Pennsylvania, prosecutor testified that a judge later signed off on a search warrant for the bag, a few hours after the searches were completed. The warrant, she said, provided a legal mechanism for Altoona police to turn the evidence over to New York City detectives investigating Thompson’s killing.

As he has throughout the case, Assistant District Attorney Joel Seidemann described Thompson’s killing as an “execution” and referred to his notebook as a “manifesto” — terms that Mangione’s lawyers said were prejudicial and inappropriate.

Judge Gregory Carro said the wording had “no bearing” on him, but warned Seidemann that he’s “certainly not going to do that at trial” when jurors are present.