On the evening of Sept. 8, Chamica Adams and a friend planned to attend a $10, open-bar happy hour at the District Lounge and Grille, a popular Adams Morgan hangout. So when Adams picked up her friend, according to her attorney, the two had worked out a plan that her friend would serve as the designated driver for the evening.

Over the next 90 minutes, while partying at the bar and restaurant in the 2400 block of 18th Street NW, attorneys say Adams had three drinks: two Tequila Sunrises, a combination of tequila and orange juice, and a green zombie, OJ with four types of rum, including a splash of 151-proof rum.

Then, about 8:30 p.m., Adams told her friends that she was ready to leave so she could get home to put her 5-year-old son to bed. But her friend allegedly chose to stay at the club, and so Adams climbed into a friend’s white Dodge Charger.

A few blocks from the nightclub, authorities say, Adams, 23, whose blood-alcohol level was nearly twice the legal limit for driving in the District, struck two of a group of four pedestrians standing on a traffic island waiting for the light to change as they walked to dinner. Adams, speeding south on 18th Street NW, plowed into them as she tried to turn left onto U Street, authorities said, throwing the two women into the air. Adams’s vehicle then crashed through the front window of a restaurant near 18th and U streets NW. Police later found an almost empty bottle of Grand Marnier in the car’s glove box.

One of the pedestrians, Julia Bachleitner, 26, an Austrian student who had arrived in the United States two weeks earlier to attend Johns Hopkins University’s international graduate school program, was killed. Her classmate, Melissa Basque, who was standing next to her, was severely injured. No one in the restaurant was injured.

Monday, in a crowded courtroom, a D.C. Superior Court judge sentenced Adams to nearly 31 / 2 years in prison.

“There are not enough words in the vocabulary to express the sorrow. I am at a loss of words,” Adams said before the judge issued the sentence.

“My heart hurts as if I lost my best friend, not a stranger,” Adams said, wiping away tears. “The memory of the accident is the pure definition of torture.”

In December, a D.C. Superior Court grand jury indicted Adams on several counts, including involuntary manslaughter, aggravated assault and driving while intoxicated. In March, Adams pleaded guilty to involuntary manslaughter.

Prosecutors disputed Adams’s tale of a failed designated driver arrangement, alleging that Adams knew she had a drive of about 40 minutes to her Mitchelville home and that none of the 90 or so cellphone calls to and from her phone that night involved Adams setting up an alternate way to get there.

Assistant U.S. Attorney Michael Truscott asked the judge to sentence Adams to seven years. Truscott said Adams “should have known better,” describing the accident as the “nightmare every community has” and a “textbook example of mixing alcohol and driving.”

It was an emotional, often tense, hearing, with family members and friends of Bachleitner’s, including about a dozen of her classmates, filling up one side of the courtroom, and Adams’s parents, family and friends filling several rows on the other side.

But it was the angry, sorrow-filled pleas from Bachleitner’s mother, twin sister and fiance that gripped the courtroom.

“I am a twinless twin, dead on the inside,” Bachleitner’s sister Kathrin said. “The irresponsible actions of Chamica Adams are inhuman. This whole tragedy is her fault alone.”

The sisters’ mother, Gundren Bachleitner, described how Julia was the older twin and the first of the infant girls to smile. Adams, she said, “destroyed my life. She destroyed the life I created.”

At times, Adams bowed her head, wiping away tears with her shackled hands. Last month, Bachleitner’s family filed a $20 million civil suit against Adams and the C. Fields Group LLC, the owner of the District restaurant and lounge. In an e-mailed statement, owner Benjamin Dalley said Adams had been drinking before she arrived at his bar.

Adams’s attorney, James W. Rudasill Jr., said his client’s biggest mistake was “her inexperience with alcohol.” Rudasill said his client was under psychological evaluation at the D.C. jail.

Adams pleaded for mercy from Judge Gerald I. Fisher.

“I am not the monster they believe me to be or a crazed party girl the media makes me out to be,” she said.

In arriving at his sentence, Fisher said he considered Adams’s lack of a criminal record. The judge also learned that a defendant charged with involuntary manslaughter in Austria faced a maximum sentence of one to three years in prison.

“I think the decision to take the keys and walk out of the restaurant is significant,” Fisher said. Fisher, who called the case “sad” and “chilling,” also sentenced Adams to five years each of probation and supervised released.

Fisher encouraged Bachleitner’s family to try to forgive. “Unless and until you forgive Ms. Adams, you will never get over this,” he said.