PHOTOS: Boston bombing suspect hides in Watertown boat

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WATERTOWN, Mass. — The Massachusetts State Police has released photos of the boat where the second marathon bombing suspect was found, giving the public a new perspective of the manhunt.

The images were shot by the State Police Air Wing and show the heat signature of a person lying down.

Authorities said they were tipped off when a Watertown man, cooped up in his house all day because of a “shelter in place” order, finally stepped outside when the order was lifted.

David Henneberry said he soon noticed the tarp covering the boat in his backyard was flapping in the wind and a retention strap was cut. He said he also noticed a small amount of blood on the tarp.

“He basically stuck his head under the tarp, noticed a pool of blood,” Henneberry’s stepson Robert Duffy told CNN.

Henneberry said he discovered a man curled up in a ball.

Duffy said at that point he became an “absolute hero” and contacted law enforcement.

Authorities arrived and evacuated Duffy’s stepfather. Using a bullhorn, they called out to the suspect: “Come out with your hands up.”

But the bloodied man refused.

“We used a robot to pull the tarp off the boat,” David Procopio of the Massachusetts State Police said. “We were also watching him with a thermal imaging camera in our helicopter. He was weakened by blood loss — injured last night, most likely.”

A gunfight followed, with more than 20 rounds fired.

Authorities eventually rushed the boat and took 19-year-old Dzhokar Tsarnaev into custody.

Officials said the suspect was hospitalized in serious condition. A Justice Department spokesperson said he could soon face federal terrorism charges.

Tsarnaev and his older brother, Tamerlan Tsarnaev, are accused of setting off bombs at the marathon Monday, killing three people and leaving more than 170 wounded.

On Thursday night, they allegedly killed a Massachusetts Institute of Technology police officer before the older brother was killed in a shootout with police.

CNN contributed to this report.