Count-Down

Dzhokhar Tsarnaev sauntered along, passing Martin Richard, the eight-year-old boy who was killed by the blast from the bag carried by older brother Tamarlan Tsarnaev, who looked straight in the eyes of Jeff Bauman waiting at the finish line for his girlfriend, as he lowered his backpack to the ground and walked off. Jeff Bauman's life was saved by bystander Carlos Arrendondo, applying emergency triage under first-responders arrived.

Dzhokhar had casually dropped his backpack, and wandered off unflinching at the first blast, unperturbed by the second.

Killed along with little Martin Richard were Krystle Campbell, 29, and graduate student Lu Lingzi, 23.  About 180 bystanders to the Boston Marathon were wounded, and some of them were maimed for life, losing a limb, two limbs, suffering blast damage from the projectiles that spurted madly from the explosions; bits and pieces of steel, ball bearings, nails, inimical to human flesh.

Mr. Bauman, legs amputated, described for the FBI from his hospital bed the facial characteristics of Tamarlan Tsarnaev.

Later that same night, Dzhokhar tweeted: "Ain't no love in the heart of the city, stay safe people". This is one sweet young man, he must be, everyone who knew him declares that to be fact, including his doting father. The next day Dzhokhar reclaimed a vehicle at a local auto body shop, left several weeks earlier, not yet completely repaired.

And the day after that he was back at the Dartmouth campus of University of Massachusetts.

That was a normal, everyday Wednesday. Young Dzhokhar worked out at the gym. He slept in his dorm room. He went to a campus party with friends. "He was just relaxed", said a friend. Earlier in the day he had tweeted: "I'm a stress free kind of guy". And so, evidently, he was. A placid temperament in an innocent mind is a good thing, everyone could agree with that.

The next day the FBI authorized the public release of images of two men taken from videos, some of many that the crowd of cheering race celebrants had taken and handed over to authorities who pleaded for public help in the identification of the possible bomber/s. "Somebody out there knows these individuals as friends, neighbours, co-workers, or family members of the suspects", urged Special Agent Rick DesLauriers.

Students at Dzhokhar's dorm joked about, just the way young people do. They offered the opinion that Suspect 2 "could be Dzhokhar". Then, of course, laughed it off. Just kidding, guys. Light-hearted kidding, good friends, all. That night the brothers were out and about. In two vehicles, with plenty of unfriendly explosive devices stored within, and revolvers, just in case. One driving a hi-jacked vehicle, the other a Honda Civic.

The hi-jacked SUV still had the owner's cellphone in it, which allowed police to track it. And then, at one in the morning, a Watertown police officer saw the vehicle, identified it, and followed it. The cars stopped, the drivers firing. An additional five officers arrived, and all engaged in a firefight involving, they estimated, over 200 rounds, homemade grenades and a pressure-cooker bomb.

"The first brother [Tamerlan] comes out from under cover and starts walking down the street shooting at the officers", explained Watertown police chief Edward Deveau. When his ammunition gave out, one officer tackled him. Suddenly police moved out of the way as little brother dove behind the SUV's steering wheel and drove right at them. "He runs over the brother and drags him down the street", said Chief Deveau.

Tamerlan Tsarnaev was pronounced dead at 1:35 a.m. in hospital. That was some tense, action-packed half-hour. Transit police officer Richard Donohue had been badly wounded in the gun battle, and the others rushed to his aid.  Dzhokhar exited the SUV, and managed to vanish into the surrounding darkness. Not to be seen again until many hours later, when a call from a home owner to 911 said a bloodied man was lying in his boat in his backyard.