Massachusetts State Police used thermal imaging from a helicopter and a robotic device to see what was inside that boat.
The images caught by the helicopter helped police officers on the ground determine that there was a person on the boat and that person was moving.
On the video you can see officers use “flash bang” grenades to stun Tsarnaev. You can then see him climb out of the boat
The State Police released the video of those thermal images to the public Saturday.
Click above to watch that video.