When Christina Korbe heard a loud banging noise at the front door of her Indiana Township home early Wednesday morning, her first thought was the safety of her two children, a brother said.

"She'd die for those kids. They were her life," Bert Roland Jr., Ms. Korbe's brother, said yesterday.

One person did die in her home that morning: FBI Special Agent Samuel Hicks. He was hit by a single shot when Ms. Korbe fired her .38-caliber handgun from the top of a staircase, according to court records.

Ms. Korbe told police and relatives she didn't know law enforcement officials had entered the house to apprehend her husband, Robert, on drug charges. She feared her home, on Wood Runs Road, was being robbed, and her protective maternal instincts kicked in.

"They busted the door. She was scared. She shot," said Mr. Roland, who talked to his sister on the phone Wednesday night after she'd been arrested.

"I didn't know. I didn't know," she told her brother. He said she cried as they spoke.

Mr. Roland recounted the story as he stood in front of his parent's home on a quiet residential street in Shaler, where several of Ms. Korbe's six siblings gathered yesterday and expressed shock at this week's turn of events.

They described her as a doting stay-at-home mom who focused her energy on her two children, 10-year-old Taylor and 4-year-old Nicolas, from organizing birthday parties to becoming active at the Fox Chapel Area School District.

Ms. Korbe is also a striking blonde who likes to wear designer clothes.

"She took care of herself," Mr. Roland said. "She was a good-looking woman."

She and Robert Korbe met at Fox Chapel High School and married in 1994. Mr. Korbe has a lengthy criminal record stretching back 17 years, but Ms. Korbe's own record until this week was sparse: a 1991 charge for possession of marijuana that was later withdrawn.

The couple gradually upgraded their lifestyle, starting out in an apartment in Stanton Heights and briefly living in a trailer.

Mr. Korbe, owner of Korbe Deluxe Car Care and D&J Variety Store on Main Street in Sharpsburg, eventually earned enough money to buy their home and give his wife expensive gifts.

Mr. Roland said his sister didn't know the details of her husband's business or the source of his income.

"He was very secretive about things," Mr. Roland said. "Nobody knew everything he was doing."

He now faces federal charges of conspiracy to distribute five kilograms or more of cocaine and 50 grams or more of crack, and two counts of possession with intent to distribute cocaine. A formal hearing in federal court is scheduled for Monday.

Mr. Korbe's mother, Antoinette Korbe, said she threw her son and daughter-in-law out of her house three years ago when she saw signs of drug dealing. She blamed Christina Korbe for much of the trouble now facing her son.

"She wants to live the high life and my son supported her that way," she said. "She knew everything he was doing."

In 2006, the couple filed a protection-from-abuse order against Antoinette Korbe, accusing her of making "terroristic threats" against the family and repeatedly showing up at Taylor's school bus stop. She denied doing anything wrong.

Mr. Roland said his sister had a license to carry a gun, and she had learned how to shoot with their father at a firing range.

Yesterday, the Korbe children were at her parents' home.

"She's worried about her kids," Mr. Roland said. "That's her main concern."