This Monday, April 15, 2013 photo provided by Bob Leonard shows second from left, Tamerlan Tsarnaev, who was dubbed Suspect No. 1 and third from left, Dzhokhar A. Tsarnaev, who was dubbed Suspect No. 2 in the Boston Marathon bombings by law enforcement. This image was taken approximately 10-20 minutes before the blast. AP Photo/Bob Leonard This Monday, April 15, 2013 photo provided by Bob Leonard shows second from right, Tamerlan Tsarnaev, who was dubbed Suspect No. 1 and third from right, Dzhokhar A. Tsarnaev, who was dubbed Suspect No. Bob Leonard and his family were Boston Marathon veterans and he preferred a spot not too far from the finish line to shoot runners as they concluded their 26.1-mile run. The area was less congested and over the years he learned that the men and women in the lead there usually went on to win. With his Nikon, Leonard snapped about 10 to 20 photos a minute Monday, capturing group after group of finishing runners and the crowds lining the route. Three days later, when the FBI released images of the suspects in the Boston Marathon bombing, Leonard used the time stamp shown on them to narrow his search of the hundreds of photos he had took that day. He realized that he, too, had photos of the faces of the two men authorities were searching for. He uploaded them to the FBI and Friday morning, he saw his cropped photos all over the morning news. "That finally gave them a good facial picture," the 58-year-old electrical engineer said. It was a pretty good breakthrough. The two men were later identified as brothers, 26-year-old Tamerlan Tsarnaev, who was killed in shootout with police overnight Friday, and 19-year-old Dzhokhar A. Tsarnaev, distinctive in his backward white baseball cap. The younger man was captured Friday night after a daylong siege of a Boston suburb. "They actually stood in that corner for quite a bit of time," Leonard of Taunton, Mass., said of the men, just before the younger brother was caught. After combing the digital images, he was sure he had something the FBI could use. He tried to upload them to an FBI site that it had asked the public to use. Then he called the hotline number and was on hold for about 40 minutes, the response was so overwhelming. He finally got an FBI spokesman, who told him to upload them to another site. Within 20 minutes, someone from Homeland Security called him back. "They were on the news ... clear pictures of the two subjects and those were the pictures that I sent in," said Leonard, who started photography as a hobby when his sons played high school sports. He was not the only picture-taker to help with images of the suspects. Seconds after the bombs exploded, David Green pulled out his smartphone and took a photo of the chaos developing a couple hundred yards in front of him - the smoke, the people running in panic. It wasn't until Thursday, when officials released surveillance video of the two suspects, that Green realized what he had - a picture of Dzhokhar A. Tsarnaev walking away from the scene. Lubin said Thursday, after the FBI released photos of the two suspects, that he decided to take a closer look at Green's photograph - on the off chance Green had captured anything unusual. There in the lower left corner was Dzhokhar Tsarnaev walking around a corner, his backward white baseball cap standing out amid the dozens of panicked people fleeing. Green contacted the FBI, which told him to send them a copy of the photograph. "He is calmly walking, without panic," Green said of Dzhokhar Tsarnaev. Leonard also took pictures of the chaotic aftermath, smoke five stories high from the explosions that he said were deafening. He also saw a person who lost a limb before police rushed everyone away from the scene. "The sense of loss tears your heart apart when you hear the victims' stories," said Leonard, who has lived in Taunton, about 30 miles south of Boston, since 1986 and knows what the race means. It's just so senseless. Associated Press writer Russ Bynum in Jacksonville Beach, Fla., contributed to this report.