Accidental witness was just a hair’s breadth from murder

It was after 10 o’clock at night, and Nate Harman figured he had put in a long enough day crunching numbers.

It was April 18, 2013, and he was in his first year of a five-year PhD program in math at MIT. He jumped on his bike and rode up the concrete path, toward the Koch Institute. He noticed that an idling police cruiser was parked outside the Koch.

As he pedaled toward the cruiser, he thought it looked kind of weird.


“When I went by, the front door was open. There was someone leaning into the driver’s side door,” Harman said, sitting on the witness stand in Courtroom 9 of the federal courthouse. “They stood up, startled, when I rode my bike by.”

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How close were you, Bill Weinreb, the prosecutor, asked.

“Within five or six feet,” Harman replied. “He snapped up and turned around. He looked startled.”

Did he look at you?



Did you get a good look at him?


The guy was wearing a dark sweatshirt with some writing on it that Harman couldn’t remember. The guy had a distinctive face.

“I remember thinking he had a big nose,” Nate Harman said.

Bill Weinreb asked Nate Harman if he saw that man in the courtroom.


“He’s right there,” Nate Harman replied, pointing at Dzhokhar Tsarnaev, fewer than 10 feet away, at the defendant’s table. “He has a blue shirt on.”

At that moment, Dzhokhar Tsarnaev appeared to lean forward in his chair, seemingly sticking his chest out.

Back on that night, Nate Harman thought little of the chance encounter and kept pedaling.

“I just laughed, actually,” he said.

He thought it was kind of funny, that he had spooked that guy just by pedaling by.

It was only later, when he found out who and what he had come across, that Nate Harman realized how close he may have come to being the fifth person killed by the Boston Marathon bombers.

A video from an MIT security camera captured the murder of MIT police Officer Sean Collier.

Two shadowy figures walk across the courtyard and round the corner to find Collier sitting in his idling cruiser. One of those individuals extends his arm and what appears to be a muzzle flash lights up the screen. Simultaneously, the brake light on Collier’s cruiser flashes, most likely from Collier’s foot hitting it as he was shot.

Then just a few seconds later, Harman comes cycling into the bottom of the screen, heading toward the cruiser.

Harman didn’t see Tamerlan Tsarnaev. In her opening statement, Judy Clarke, one of Dzhokhar Tsarnaev’s lawyers, said it was Tamerlan who shot Collier. But Harman’s testimony puts Dzhokhar right at the scene, suggesting Dzhokhar was trying to get Collier’s gun.

MIT police Sergeant Clarence Henniger, who found the mortally wounded Collier just minutes after Harman pedaled away, said somebody had tried to pull Collier’s .45-caliber Smith & Wesson pistol from his blood-soaked holster but had been thwarted by its elaborate security system.

“The second latch was down,” Henniger said. “To extract the weapon, there’s a button you have to press.”

Neither Tsarnaev brother knew about that button.

Bill Weinreb put up a couple of photos we hadn’t see before. It shows Dzhokhar Tsarnaev in the lobby of some building. He’s wearing a grey Adidas sweatshirt and a white cap.

Do you recognize this person? Weinreb asked

“Definitely could be that person,” Nate Harman said.

What about the sweatshirt?

“Definitely could be,” he replied.

Same kind of cap?

“Yeah, it was that kind of cap.”

Nate Harman is 24 years old and he was pretty composed on the witness stand. And he didn’t hesitate when asked to point out Dzhokhar Tsarnaev. But during a pause in his testimony, Nate Harman poured himself a cup of water, and his hands were shaking noticeably.

Who could blame him?

Dzhokhar Tsarnaev’s lawyers didn’t even bother to cross-examine him, even though he put their client right in the middle of the murder of a police officer, one of the 17 charges for which he faces the death penalty if convicted.

Nate Harman, an accidental witness, left the courthouse with an FBI agent at his side.

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MIT’s fallen officer built enduring connections

Kevin Cullen is a Globe columnist. He can be reached at