A Calhoun College junior arrested last month for firing a handgun in the Beta Theta Pi fraternity house was taken into custody Thursday on bomb-making charges.

David Light ’09, 21, of Woodland Park, Colorado, was charged with criminal attempt to commit the manufacture of bombs; 12 counts of reckless endangerment in the first degree; eight counts of breach of peace in the second degree; 23 counts of possession of armor-piercing ammunition; and one count of manufacture or storage of explosive material near property of another.

Light was in the process of posting $250,000 bond on Thursday and was ordered to surrender his passport. He remains under an emergency suspension from the University.

In July, Light was arrested after a visitor to Beta reported observing Light firing a handgun in the direction of the ceiling of the fraternity’s living room. Police then found various chemicals and a cache of weapons in Light’s bedroom, including what the authorities described as several illegal assault weapons.

His attorney, William Dow III, told The Associated Press that Light would plead not guilty to the charges.

“Unfortunately because of the timing and the environment, this is going to be projected on a larger stage than it really merits,” Dow said. “We’re talking about a college student who allegedly made significant errors of judgment.”

Light, a biology major, told police that he had been interested in chemistry and the sciences as early as middle school, and enjoyed performing experiments with various chemicals to create “really cool stuff.”

After his arrest last month, the police obtained warrants to search Light’s computer and Yale e-mail account. In his e-mails, Light talked excitedly about playing with chemicals and bragged about the weapons he fancied, according to a police affidavit.

“I may be crazy,” he wrote to a friend in February, “but I try not to be too stupid and stay out of jail.”

In the messages, Light talked of his plans to dump pounds of chemicals into the New Haven Harbor to create a “fireball” and “smoky awesomness” [sic]. The explosion, he wrote, was “gonna be friggin amazing.”

In another e-mail, he asked a friend “how soon do you want to do something dangerous???”

Light also sent other e-mails, including some to other Yale students, about his plans to create different chemical explosives and about the .50-caliber “anti-tank rifle” that he was “sooo [sic] excited” his parents were buying him for his birthday. His mother only hesitated, Light wrote to a friend, when a package of “tank shells” for the gun arrived at their home. “My mom saw them and was like … Can we reverse the order?!” Light told the friend.

“It was pretty funny,” he said.

The affidavit only quoted Light’s e-mails in bits and pieces and did not provide significant context for the choice quotations that appear incriminating. Dow suggested Light may have been joking or exaggerating in some of the conversations quoted by the authorities.

“Sarcasm has been a key ingredient of the Yale campus since the days of [fictional character] Dink Stover and [cartoonist] Garry Trudeau,” a member of the class of 1970, Dow said.

The arrest warrant also gave more details about the Yale Police Department’s raid on Beta last month. Five YPD officers and two members of the Connecticut State Police’s Urban Violence Task Force executed the search warrant at 11 p.m. on July 16, using a key provided by the building’s landlord to enter Light’s room, according to the affidavit.

There, the authorities found a .50-caliber rifle on Light’s bedroom floor, as well as several rifle cases on the floor and another case containing three pistols. In Light’s closet, police found an unlocked gun safe containing other rifles, as well as several other weapons propped up against the wall in Light’s closet.

Police also found a cardboard box filled with assorted liquid and dry chemicals, and, according to the affidavit, a YPD officer was injured after coming in contact with a substance in the box. Det. Martin Buonfiglio suffered a burn to his right hand and was brought to Yale-New Haven Hospital for treatment, according to the affidavit.

The YPD then evacuated the building, and the New Haven Fire Department was called at 12:08 a.m. Fire officials broke open several locked doors to ensure no one was left in the building, according to the affidavit, and the state Department of Environmental Protection removed chemicals from Light’s bedroom, including flash powder and a 16 oz. jar of mercury.

The cardboard box also contained what were determined to be bomb-making supplies, including cylindrical cardboard tubes, endcaps and fuses, the police said. Light had covered his bedroom’s smoke alarm in plastic, according to the affidavit, perhaps to ensure any fire or smoke from his experiments did not set off the fraternity’s alarm.

Light himself arrived at Beta in the course of the search and was approached at gunpoint by a YPD sergeant as he parked his 2006 Kia in front of the fraternity. He was charged at that time with two counts of illegal possession of assault rifles, unlawful discharge of a firearm, reckless endangerment in the first degree, threatening in the second degree and breach of peace in the second degree. Light was released on $150,000 bond.

A few weeks later, the national Beta Theta Pi organization voted to disband its Yale chapter, in part because of Light’s arrest, although the chapter has vowed it will stay open, just as an independent, local fraternity. Light, meanwhile, is next due in court on Sept. 25.