Unanswered questions regarding the Boston bombing

The May 9, 2013 House Homeland Security Committee hearing on the Boston Marathon terrorist attack was a melodrama of diversionary discourse.  From former Senator Joseph Lieberman’s attempts to blame the FBI and Russian Federation for incomplete sharing of information to Boston Police Commissioner Edward F. Davis’ focus on response rather than prevention to Professor Erroll G. Souther’s denunciation of thoughtcrime, there was a concerted effort to avoid the most important questions, those being: 

Where were all the human surveillance operatives in the minutes before the bombs exploded, assuming the operatives were active? 

The casual reader may question the existence of plainclothes surveillance operatives, as distinct from undercover police officers.  The FBI has its Special Surveillance Group, unarmed employees without powers of arrest whose operations were revealed in some detail after the Robert Hanssen affair went public.   

The Boston Police Department has its Field Operations Group as the likely locus of spookery.  What intelligence division would be complete without its very own FOG?

I’m personally ambivalent about these organizations, because they are useful for variously motivated harassment.  Boston deploys them in summertime on creepy photographer patrol to ensure this stuffy city does not deviate from its prudish Puritan and Irish-Catholic traditions.   

They are also used for ground level human surveillance of parks and public squares to suppress the drug trade.  The drug gangs in northern Mexico even field their own operatives on the plazas and street-corners of Ciudad Juarez, Nuevo Laredo and Reynosa – as young as thirteen, called panteras y halcones – to identify and report opposition drug gangs moving into contested territory.  
So, let’s accept without FOIA-generated documents that these human surveillance operatives exist, are not unicorns or phantasms, and operate for different purposes and at varying degrees of professionalism…  Where and what were Boston’s human surveillance operatives doing on April 15, 2013 between 2:34 and 2:49 pm? 

What, if anything could human surveillance operatives have done to: 

1. Recognize the Tsarnaevs as suspicious actors before they dropped their bomb-laden rucksacks – without prior intelligence?
2. Recognize the rucksacks as suspicious after they had been dropped and the Tsarnaevs had moved on?
3. Clear the area around the suspicious rucksacks?
4. Remove or dispose of the suspicious rucksacks after they had been dropped but before they exploded? 
5. Were the human surveillance operatives reduced or released shortly before the rucksacks, now known to have contained bombs, were dropped and detonated? 

And regarding the behavior of the Tsarnaevs themselves: 

6. (If the answer to #5 is yes,) did Tamerlan Tsarnaev, sufficiently skilled in counter-surveillance after his visit to Chechnya to recognize a lifting of the security presence, take that as his cue to proceed with the bombing?

7. Why did the Tsarnaevs postpone the bomb detonations until very late in the marathon instead earlier, when a more crowded finish line would have ensured more victims? 
- Did they procrastinate? 
- Did they desire to target a crowd composed mostly of U.S. citizens instead of a more international crowd? 

A useful postmortem investigation should begin from an unpleasant premise: The proximate cause of the Tsarnaev’s attack wasn’t a lack of intelligence-sharing months earlier, but a lapse or series of lapses between the moment the Tsarnaevs first started walking through the crowd and the moment the first bomb detonated.