A car makes a left turn across River Road in Bethesda July 10 at the scene of a February collision that killed three. (Dan Morse/The Washington Post)

Behind the wheel of a turbocharged BMW, the 20-year-old shot down River Road in Bethesda at 115 mph — 70 over the posted limit. He was heading home after picking up Chinese food for his family.

Ahead, on the other side of a slight rise, a Chevrolet Volt carrying a family of four was about to make a left turn from the opposing lanes. They were on their way to a high school play and were five minutes from curtain time.

The crash was thunderous.

The BMW slammed the Volt broadside, killing three of the family members despite the heroics of horrified witnesses: the men who lifted an uprooted metal sign to try to pry open a door of the Volt; the ex-CIA officer who smashed a tool he had in his pocket into the car’s rear window; the petite doctor who was passed through the broken window into the Volt to try to give medical help.

“I did it! It’s all my fault!” the BMW driver could be heard yelling.

That driver — Ogulcan Atakoglu — signaled in court records this week his intent to plead guilty to three counts of vehicular manslaughter after a lengthy police investigation into the Feb. 27 crash near Walt Whitman High School. The results of that probe, including Atakoglu’s speed and statements from witnesses, are detailed by Montgomery County police in a 16-page collision reconstruction report obtained through a public records request by The Washington Post.

Atakoglu agreed to the plea ahead of anticipated indictments, according to court records. “He wants to take responsibility,” said his attorney, David Felsen. “He has been profoundly distraught since the moment this happened.”

Atakoglu, who has a prior conviction for negligent driving and speeding, was sober and wasn’t racing. He tried to avoid the crash, hitting the brakes, but struck the Volt at about 75 mph.

By pleading guilty to vehicular manslaughter, he is admitting that his speed alone was a form of gross negligence. The plea agreement is not binding, and Atakoglu could back out before a hearing scheduled for Aug. 8 before Montgomery County Circuit Court Judge Mary Beth McCormick.

He could face up to 30 years in prison under Maryland statute. State sentencing guidelines, which are not mandatory, call for a penalty of three months to 12 years in the case. Prosecutors can seek the maximum penalty, according to court records.

The survivor from the Volt, Helena Buarque de Macedo, was 15 when in an instant she lost her mother, father and only sibling. She was hospitalized with life-threatening injuries but returned to Whitman in time to finish her sophomore year. Principal Alan Goodwin said she could be seen talking to her friends, appearing, at least, to somehow be getting by.

“She seems to be doing all right, considering the horrors she is going through,” he said. “She did well in school. She’s a bright girl.”

Helena lives with grandparents in Bethesda and has support from extended family, Goodwin said.

Last month, she and an uncle went to Whitman’s graduation ceremony to honor her 18-year-old brother, Thomas. Known as Tommy, he was an exceptional student who had taken Advanced Placement courses in physics, economics and multivariable calculus and was aiming to attend an Ivy League college.

“We are just thrilled to have her back,” Goodwin said from the stage.

In front of a cheering crowd, Helena was handed Tommy’s diploma.

‘Out of nowhere’

Atakoglu, the son of an accomplished jazz pianist and composer from Turkey, had attended the Bullis School. In 2013, he wrote and narrated a nine-minute documentary about the Civilian Conservation Corps that used his dad’s music in the background. “He is an articulate, polite kid,” said Felsen, his attorney.

That same year, police alleged that he was driving erratically and at more than 85 mph on Interstate 270, according to a recorded court hearing. A District Court judge found Atakoglu guilty of reckless driving and an unsafe lane change. The judge reduced the speeding violation to 64 mph because the officer hadn’t calibrated his speedometer. Atakoglu paid $639 in fees and court costs. On appeal, Felsen struck a plea deal with prosecutors that reduced the reckless driving count to negligent driving.

“I’d like to apologize for speeding and behaving in a negligent manner on the roads,” Atakoglu told a judge. “And I’ll make sure it won’t happen again, Your Honor.”

On Sept. 23, 2015, Atakoglu was cited for negligent driving and tailgating in Rockville. The case was dismissed in court after the police officer acknowledged that he couldn’t positively identify Atakoglu.

On the night of the River Road crash, Atakoglu went to a friend’s house before picking up the Chinese food, according to the collision report. He headed west on River Road, away from Washington, toward his family’s house between Rockville and Potomac. The blue 2016 BMW M235i was being leased by his father, according to Felsen.

The Buarque de Macedo family lived nearby in a Bethesda home where Michael and Alessandra, both 52, ran successful software-development and accounting businesses, according to friends.

It wasn’t uncommon for families in the area to head to a play at Whitman. On tap: the 1982 comedy “Noises Off.”

In a 2016 Volt electric car, the family was traveling east on River Road when their vehicle stopped just before 6:55 p.m. in the far-left turn lane near Pyle Road, preparing to turn and cross River Road toward the school.

Crash investigators later reviewed information in the two cars’ “black box” event recorders, spoke with witnesses and estimated sight lines for that hour just after sunset in late February. They concluded that the drivers of the BMW and the Volt could see each other’s headlights after the BMW crested the hill — a spread of about 1,000 feet.

Two motorists lined up behind the Volt, also on their way to the play, described the Volt driver as cautious and hesitant, waiting for cars to pass. When the Volt finally crossed River Road, it accelerated from 2 mph to 10 mph, according to the reconstruction report.

It isn’t clear from the report when the Volt driver — Michael Buarque de Macedo — spotted the BMW’s headlights. But investigators concluded that at that time of night, with headlights coming directly at him, it would be hard to gauge speed.

With less than 800 feet between him and the intersection, Atakoglu was still traveling at 115 mph, according to the collision report, fast enough to cover about half the length of a football field every second.

In a statement he wrote for police, Atakoglu described what happened: “A car coming in the opposite direction on River Road made a left turn in front of me, and I flashed my lights at it.”

People in the car behind the Volt saw the BMW coming, as one witness put it, “out of nowhere.”

“We all screamed and I said: ‘They’re going to hit,’ ” she said.

Atakoglu braked 2.5 seconds before impact, according to investigators, and swerved slightly right, ramming into the Volt after it had crossed most of the intersection and pushing it into a ditch.

“The impact was tremendous,” a witness reported. “Glass went everywhere,” said another.

Immediately behind the Volt, the driver of a Mini Cooper, a security consultant who had previously worked as a CIA officer, jumped out and ran to the Volt. He and others tried to pry the door and then he smashed the back window. All the while, he told detectives, he saw no response from anyone in the car.

Behind the Mini Cooper were another driver, her two children and two of their friends. She went to the Volt, holding a flashlight while others tried to open the door.

About the same time, Raya Kheirbek, a palliative care physician, happened upon the scene with her son. She saw a crushed car but no ambulances yet. She ran to it, telling several people she was a doctor.

A man lifted the 5-foot-1, 115-pound physician through a broken window of the Volt. She wiggled into the front.

To her left, she saw the slumped driver, his head leaning into a deployed air bag. He was gasping — terrible sounds Kheirbek recognized in someone dying.

Leaning on the driver was a front-seat passenger, a tall young man. Kheirbek checked but could find no pulse, she told The Post in a recent interview expanding on an account she previously told Bethesda Beat, a daily local news service.

Kheirbek wiggled back, looking to her right: a woman with no movement in her chest.

“I heard a voice,” Kheirbek said.

To her left was a young girl with long hair covering her face.

“Are you okay?” Kheirbek asked.

Helena Buarque de Macedo moved her head slightly.

Kheirbek put her arm around the girl.

“Stay strong,” Kheirbek said. “Help is going to be on the way.”

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