HANOVER TWP., Pennsylvania -- An explosive device was found in a checked piece of luggage at Pennsylvania's Lehigh Valley International Airport on Monday, according to a criminal complaint.
The passenger, Mark Muffley of Lansford, Pennsylvania, is now in custody, and an FBI agent testified that Muffley confirmed he was aware he had the explosive in his bag.
Muffley, 40, was set to take an Allegiant flight from eastern Pennsylvania to Florida's Orlando Sanford International Airport.
The device hidden in the bag's lining was a circular compound, about 3 inches in diameter, that had two fuses and powder concealed in wax paper and plastic wrap, according to the criminal complaint.
The "powder is suspected to be a mixture of flash powder and the dark granulars that are used in commercial grade fireworks," the complaint said. "The black powder and flash powder are susceptible to ignite from heat and friction and posed a significant risk to the aircraft and passengers."
The bag also had "a can of butane, a lighter, a pipe with white powder residue, a wireless drill with cordless batteries, and two GFCI outlets taped together with black tape," the complaint said.
Sources familiar with the investigation told ABC News that based on a preliminary assessment, the device contained flammable, explosive components but was not operational and not constructed to go off in flight. The investigation into the suspect's background is ongoing to better understand why he allegedly packed these materials, the sources said.
The device was detected during "routine screening," when the suitcase triggered an alarm when it entered the baggage screening unit, the Transportation Security Administration said in a statement. While inspecting the baggage, a TSA officer "located an item inside the suitcase that appeared to be suspicious and was believed to possibly be a live explosive device," the agency said.
An airport spokesperson said the suspicious package was discovered shortly after 11 a.m. Monday and the west side of the airport's main terminal was shut down.
Muffley was paged over the airport's public system to come to the security desk, the criminal complaint said. Five minutes later, security cameras showed Muffley leaving the airport.
The package was removed from the airport and the closed portion of the terminal reopened shortly before 2 p.m., the airport spokesperson said.
FBI and local law enforcement bomb technicians who responded to the scene determined that the item "was indeed a live explosive device," TSA said.
Muffley was arrested at his home Monday night, the FBI said. He's charged with possession of an explosive in an airport and possessing, or attempting to place, or attempting to have placed an explosive or incendiary device on an aircraft.
Muffley made his first federal court appearance via videoconference Thursday for a probable cause and detention hearing.
FBI Special Agent Eddie Garcia testified that Muffley confirmed he was aware he had the explosive in his bag along with lithium batteries, butane and a small torch lighter, and he knew they were all prohibited.
Muffley's public defender, Jonathan McDonald, argued the device was "just a firework in a bag."
He claimed it was a commercial product and its only addition was a wick designed to burn slowly and that there was no way for it to explode unless someone took a lighter to one of the wicks. During cross-examination, McDonald asked Garcia if the device was a firework. Garcia replied, "It's an explosive. It may be a firework."
Prosecutor Sherri Stephan argued that it doesn't matter whether the device is a firework, because it meets the federal definition of an explosive and it posed a significant threat to the plane and passengers.
She also claimed that after the device was discovered and Muffley was called to airport security, Muffley allegedly called his girlfriend to pick him up from the airport. The prosecutor said that once Muffley was in her car, he changed his phone number in an attempt to not be tracked.
Stephan also said Muffley admitted to using drugs including methamphetamine and that the pipe found in his suitcase had meth residue in it. Stephan said he had several previous run-ins with the law, including having his probation and bail revoked on multiple occasions. Stephan said Muffley had "shown a pattern of not being able to follow the rules of release."
Judge Pamela Carlos granted detention, remanding Muffley until his next hearing.
Muffley did not speak during the hearing. When prosecutors argued he was a danger to his community and a risk of flight, he mouthed, "No I'm not."
ABC News' Jason Volack, Will McDuffie and Trevor Ault contributed to this report.