Details are still emerging over the deadly shootout that left Boston bombing suspect Tamerlan Tsarnaev, 26, dead early Friday night. One mystery that remains is whether Dzhokhar Tsarnaev, 19, accidentally killed his older brother by running over him in his haste to escape.

"He ran over his brother, and he was alive before he got run over, was run over," said Watertown Police Captain Raymond Dupuis.



Dupuis was also among the first on the scene Friday night, when Dzhokhar Tsarnaev was eventually found hiding in a boat parked in Watertown, Massachusetts resident David Henneberry's backyard. Helicopters flew over Henneberry's house, taking thermal images of his boat and the terror suspect cowering within. Officers could see Tsarnaev poking through the tarp covering the boat, and then gunfire erupted. Police used "flash-bangs," devices meant to stun people with a loud noise, and started 20 to 30 minutes of negotiation with Tsarnaev.

Dupuis stayed with Henneberry after Dkhokhar Tsarnaev was taken into custody.

"I told him everything was fine, it was okay," said Dupuis. Dupuis then walked through the house with Henneberry as he collected personal belongings and made arrangements to spend the night away from his home.

"I told him if there's anything the police department could do for him, to give me a call, and we'd take care of him," said Dupuis.

The officers involved in the chaotic events need to be taken care of as well. Dupuis and police officers faced danger at every moment - when they went through Henneberry's house, they were unsure if any bombs or traps had been set. It was only after Tsarnaev had been taken into custody that the FBI brought in teams to make sure there were no explosives in the boat, said Dupuis.

Dupuis said Watertown police officers involved in the shooting and arrest spoke to stress officers before they went home Friday night. The Bureau of Alcohol, Tobacco, Firearms, and Explosives is also sending a stress debriefing team to talk to officers on Tuesday.