Former FBI agent recalls "eureka moment" in Boston Marathon bombing investigation

In the two-part premiere episodes of the Paramount+ series FBI TRUE Season 2, viewers meet three officials — former FBI Boston Special Agent in Charge Rick DesLauriers, retired FBI special agent Nancy Aguilar and retired Watertown Police Sgt. John MacLellan — who worked together to identify, locate and apprehend the Boston Marathon bombing terrorists. Stream the episodes now on Paramount+.

Rick DesLauriers was planning to retire from his position as an FBI special agent in charge of the Boston division on April 15, 2013, when he heard the news: There were two large explosions near the finish line of the Boston Marathon.

His retirement plans, set in motion that morning, were upended so he could help lead the FBI's manhunt for the suspected bombers.

"You know, I knew we had serious work to do. I had to be a leader. I had to be strong. But for a few minutes there, I just shook my head and said, 'Gosh, I stayed in this job too long,' said DesLauriers, then a 26-year veteran of the FBI, while detailing the investigation in the two-part premiere episodes of FBI TRUE Season 2.

The carnage left three dead – Krystle Campbell, 29, Lingzi Lu, 23, and Martin Richard, 8 — and injured hundreds of others.

"It was just a scene of horrible, horrible destruction," said DesLauriers. "We had evidence on top of cars, on top of windows, on top of buildings everywhere."

Boston residents were on edge and feared more attacks. People were asked to shelter in place and avoid gathering in crowds. Law enforcement was in a race to find those responsible and prevent further attacks.

DesLauriers put together a team to sift through evidence at the scene. There, investigators found pieces of pressure cooker bombs filled with explosive materials and shrapnel – nails, screws and bolts. DesLauriers and his team declared it a terrorist attack — one that lacked a motive or a suspect.

The most significant break in the investigation came days later on April 17, 2013. That's when the FBI's Computer Analysis and Response Team showed DesLauriers surveillance video from the second bombing site. There was a man who stuck out on the video.

"He had a baseball hat with a bill pointed backward, and he had a backpack on his back. And you watch him come, and he just looks like anybody else," DesLauriers recalled. "He stands right in front of the camera and he eventually drops the backpack to the ground. And a few minutes later, he takes a cell phone call. He then hangs up on that call. And then, from the east on Boylston Street, you see the concussive effects from the first bomb going off. Everybody looks to the left, like, what just happened? This gentleman in the white hat just calmly walks away. And about 5 seconds after he leaves the field of vision. You see the second bomb go off. You see just horrible destruction – horrible destruction."

"At that point, I knew we had one of the bombers," said DesLauriers.

After collecting more video evidence from businesses along Boylston Street, the FBI pinpointed two possible suspects  — both in hats, wearing backpacks and walking along the race route.

"That was sort of the eureka moment in the investigation. We knew we had visual depictions of the bombers," DesLauriers said. "We just had to figure out who they were."

On April 18, 2013, the images were shared at a press conference, and law enforcement asked for the public's help tracking them down. When DesLauriers got home that night, he learned Massachusetts Institute of Technology police officer Sean Collier was killed while sitting in his police cruiser.

The suspects also carjacked a man in a Mercedes, who was able to escape an hour later. A police officer in Watertown, Massachusetts, spotted the car and started following them. The Mercedes stopped. Police say the driver began firing at the officer.

"About 1:00 in the morning, I got a phone call from Jeff Sallet," DesLauriers said. "Jeff told me, 'Boss, you know that those individuals who murdered that campus police officer at MIT, they're our bombers, and they're on the run right now and they're in Watertown throwing more bombs at the Watertown police officers.'"

The driver was shot multiple times. He was then run over by an accomplice driving the Mercedes. FBI did a fingerprint test and identified him as Tamerlan Tsarnaev, said DesLauriers.

"He had been on the FBI's radar screen prior to the bombings," DesLauriers added. "And then we very shortly thereafter determined he had a younger brother named Dzhokhar Tsarnaev."

Dzhokhar Tsarnaev abandoned the Mercedes in Watertown and took cover in a boat behind a nearby home. The homeowner called the police when he noticed the cover on his boat was ripped. An FBI hostage negotiation team responded to convince Tsarnaev to come out from the boat. He eventually surrendered.

"And that's when I had the most intense feeling of relief I've ever had in my life," DesLauriers said.

"As I drove back to head home, people were pouring out of the businesses, just waving American flags, cheering law enforcement," DesLauriers, who retired in July 2013, recalled. "It was one of the most moving things I had seen in my 26-year career in the FBI."