The home invasion began, a Fairfax County prosecutor said Friday, with a man posing as a police officer knocking on the front door of a tony McLean home belonging to the managing partner of a prominent law firm.

When 61-year-old Leo Fisher answered Sunday evening, the man with a badge and gun Tasered him. Fisher crumpled into the fetal position, and the man slapped a pair of flexible handcuffs around his victim’s wrists.

Then Fisher’s wife, Susan Duncan, came to the door, alarmed by the commotion. She was handcuffed, too, and shoved in a bathroom.

But the prosecutor said that this was no ordinary burglary — it was something more sordid: revenge. And that the alleged perpetrators were a pair of lawyers, one of whom was angry over her recent dismissal from Fisher’s Arlington County firm, Bean, Kinney & Korman.

Over the next several hours, Fisher and Duncan were held hostage in their home. They were tormented and stabbed so brutally that Fairfax County Commonwealth’s Attorney Raymond F. Morrogh (D) said it could only be described as a “torture session.”

Bizarrely, after the alleged suspects, Andrew and Alecia Schmuhl, fled, police found Andrew Schmuhl wearing only a diaper, authorities said. The Schmuhls, who are married, live in Springfield.

The fresh details emerged Friday during a hearing in Fairfax County Circuit Court at which Alecia Schmuhl was denied bond. A number of lawyers from Bean, Kinney & Korman filled benches in the courtroom. Fisher and Duncan remain hospitalized with life-threatening injuries.

“She presents a real and imminent danger to the law firm,” Morrogh said of Schmuhl, who stood nearby in a jail jumpsuit. “They are in fear from this woman and her husband.”

Mark Petrovich, the woman’s attorney, said that Alecia Schmuhl remained outside the home of Fisher and Duncan during the attack and that she did not know her husband planned to stab and torture them.

He said Alecia Schmuhl was suffering from depression and anxiety and was manipulated. “She was controlled by her husband,” Petrovich said.

The case has stunned the local legal community. Many wonder how such a horrific crime could touch a well-regarded law firm, strike a successful lawyer and be allegedly perpetrated by two other lawyers, who appeared to some to be rising talents.

Morrogh said that Fisher’s law firm fired Alecia Schmuhl, 30, for poor performance on Oct. 29, after nearly two years. Petrovich said that she was “pursuing legal options” over the termination.

In addition, Petrovich said the firm had accused Andrew Schmuhl, 31, of committing fraud on a refinancing application. He did not specify what type of loan it was for. Andrew Schmuhl had been out of work for 21 / 2 years after suffering a back injury in the Army. Petrovich described him as a military intelligence officer.

The pair’s anger apparently boiled over Sunday night. Andrew Schmuhl knocked on Fisher’s door about 6:30 p.m., Morrogh said. After Fisher and Duncan were bound, Andrew Schmuhl threatened them, and the victims saw him talking on a cellphone.

Morrogh said that Duncan saw someone who matched Alecia Schmuhl’s description outside the home and that Andrew flicked the lights on and off inside, as if to signal her. At one point, Morrogh said, Andrew Schmuhl fired a shot near Duncan. The bullet lodged above the bathroom door.

Eventually, he brutally stabbed Fisher in the face and upper body and turned the knife on Duncan, Morrogh said. Duncan managed to hit an alarm, and the Schmuhls allegedly fled in a car Alecia drove.

Fairfax County police arrived at the home just before 10 p.m. and took a “dying declaration” from Fisher, Morrogh said. He managed to describe the attackers’ vehicle, and a massive search began, involving dozens of officers and a police helicopter.

Officers spotted the vehicle on the Capital Beltway about 30 minutes later, and it sped away, Morrogh said. Alecia Schmuhl allegedly led the officers on a chase for four miles before being stopped in the Springfield area.

Morrogh said police found a bizarre scene: Andrew Schmuhl was naked except for a diaper. Inside the car were bloody clothes, a Taser and a gun, the prosecutor said. Morrogh did not say why Schmuhl was wearing a diaper.

Alecia Schmuhl quickly invoked her right to an attorney, Morrogh said. In the meantime, Fisher and Duncan had been rushed to Inova Fairfax Hospital in critical condition. Police said they have had difficulty interviewing them because of the extent of their injuries.

Before Friday’s hearing, Morrogh said that Fisher had managed to scrawl a note about the attack. Fisher wrote that Andrew Schmuhl had promised: “I’m going to come back and finish this job” before he left the home.

Morrogh rejected the assertion that Alecia Schmuhl was a bystander in the attack. He said that surveillance video shows her purchasing a Taser at a gun store two days earlier.

The Schmuhls have each been charged with two counts of malicious wounding and abduction by force. Alecia Schmuhl has also been charged with felony eluding and obstruction of justice.

Andrew Schmuhl’s attorney said he expected a bond hearing for his client to be held Tuesday.

Some who know the Schmuhls had a hard time squaring their polished résumés with the crimes of which they are accused.

Alecia Schmuhl speaks three languages and served on the board of the Arlington-Alexandria Coalition for the Homeless. Andrew Schmuhl was a former judge advocate in the Army. Neither had a criminal record in Fairfax County. They both graduated from Valparaiso University Law School in 2009, the school said.

“We are extremely shocked,” said Adam Lowenstein, a friend of the Schmuhls from Fort Drum, N.Y. “It seems to be completely out of their character.”

Others saw issues. Louise Wagner, the mother of a woman previously married to Andrew Schmuhl, said the couple was married for less than a year between 2009 and 2010. She said it started out well but that Schmuhl cheated on her daughter and got into debt.

“He started lying,” Wagner said.

The incident shocked Fisher’s upscale neighborhood, which is largely quiet and free of crime. The stately homes are set back from the street on sizeable lots. Neighbors said this week that Fisher and his wife were good neighbors.

Fisher manages the day-to-day operations of Bean, Kinney, which practices in a number of areas, including finance and real estate. He has more than 30 years’ experience in law.

Attorneys from Bean, Kinney declined to comment at the hearing, but the firm issued a statement.

In a statement, the law firm said “Our hearts go out to a wonderful colleague and his beloved wife. We are doing everything possible to support them through this ordeal and pray for their recovery.”

Jennifer Jenkins, Dana Hedgpeth and Matt Zapotosky contributed to this report.