1. The existence of a multitude of surveillance and personal cameras.
2. The authorities compiling and studying all those images and from that being able to identify photos of the bombing suspects.
3. The authorities going public with photos of the two bomber suspects and announcing to the public that a manhunt was in progress to apprehend the suspects.
This is what put the suspects on the run. They could no longer remain stationary because they knew that would ensure their capture.
4. The carjacking and "Danny's"escape from it. The Tsarnaev Brothers made the fatal mistake of admitting they were the bombers to the motorist "Danny" who they were holding captive.
"Danny" was able to escape from the car and call 911 to alert the authorities of the location of the suspects' whereabouts and the vehicle they were in. Which led to the police chase and the subsequent shooting of one suspect.
5. A homeowner discovering the other suspect hiding in his boat and alerting the authorities to it.
2. The authorities compiling and studying all those images and from that being able to identify photos of the bombing suspects.
3. The authorities going public with photos of the two bomber suspects and announcing to the public that a manhunt was in progress to apprehend the suspects.
This is what put the suspects on the run. They could no longer remain stationary because they knew that would ensure their capture.
4. The carjacking and "Danny's"escape from it. The Tsarnaev Brothers made the fatal mistake of admitting they were the bombers to the motorist "Danny" who they were holding captive.
"Danny" was able to escape from the car and call 911 to alert the authorities of the location of the suspects' whereabouts and the vehicle they were in. Which led to the police chase and the subsequent shooting of one suspect.
5. A homeowner discovering the other suspect hiding in his boat and alerting the authorities to it.