explosion, so pretty clear about his involvement and pretty chilling, frankly. >> all right, so while we wait on that video, i want you to look at these new infrared images released showing the final intense moments of the manhunt. stun grenades just exploded as police moved in to capture the 19-year-old, and it capped a nearly four-day search for dzhokhar and his older brother, tamerlan, and while the nation was reeling, we are getting word this morning that the brothers actually carried on with their normal lives. dzhokhar was seen working out at a college gym the day after the bombings where friends tell nbc news that he appeared normal and unfazed by the attack while older brother tamerlan was killed in the shootout. he wasn't a stranger to investigators. an article in the "los angeles times" says he told his mother about getting a call from the fbi in connection with the investigation. that report raised questions