There appears to be video capturing the Boston Marathon bomber, although not yet an arrest. I suspect that the end result will be more Ted Kazinski and less Oklahoma City or 9-11. It also illustrates dramatically that the frequent Hollywood device of secret agencies being able to access all video surveillance in real time and analyze huge volumes of it to find a particular individual is a bunch of bunk. Notably, the FBI, local law enforcement, and other criminal justice actors are taking the lead role in the investigation and achieving success with it. (Source: ABC News, national website and other news reports.)
An explosion at a fertilizer plant in a small town in Texas, just a few days after the Boston Marathon bombing, killed at least five people and injured more than two hundred, including more than a dozen critical injuries. The casualty toll was very similar to the Boston Marathon bombing but slightly worse across the board. Both events involved unexpected explosions of things known to be explosive and a facile utilitarian take on them might suggest that they are equally problematic.
But, the fertilizer plant explosion is far less worrying and rightly so. Why?
1. The fertilizer plant explosion was very likely a simple industrial accident caused by failure to exercise reasonable care in running a factory, not an intentional effort to cause malicious harm. We can see that in part because the fertilizer company suffered great damage to its own property and valued employees in the process that it didn't want, while the bomber will not suffer any harm to himself unless he is caught and his actions clearly show that he was trying not to be caught and probably believed that he might succeed in doing so (even if he was wrong).
2. There is a balancing act here. The Boston bomber's motives have no societal value to counterbalance the harm, so it remains a problem. Producing fertilizer helps farmers make food and an increased ability to make food has societal value - and it is impossible to have a large scale industrial economy that makes our lives much better without taking the risk that sometimes there will be accidents.
3. The fertilizer plant's owner or its insurance company, will almost surely provide the full amount of compensation determined to be owed to those harmed through the accident according to the dictates of the law and will cooperate within reason with the process of making that determination. The Boston bomber, if he is caught, will almost surely be unable to provide any meaningful compensation to his victims and will almost surely not cooperate in the process. This helps balance the scale.
4. Cynically and politically speaking, the upper middle class and wealthy people who drive the political system in both political parties, work in offices where they don't face these kinds of risks and can choose to live away from potentially dangerous factories without impairing their lifestyles. In contrast, a Boston Marathon bombing disproportionately impacts those very people living those very lifestyles (and on a bipartisan basis, no less, marathon running is among the least definitively partisan recreational activities out there).
On the other hand, policy measures in response to the fertilizer plant explosion have great potential to make the entire industry safer and reduce future incidents (something that mere regulatory agencies can impose without express legislative authorization, by the way).
In contrast, it is exceedingly hard to come up with policies that will prevent future Boston Marathon bombing type incidents. Indeed, as noted in a pithy way at Mother's Jones and more seriously elsewhere, acts of terrorism in the United States have declined steadily since a peak in the 1970s where systematic records started being kept to the present, with only a handful of blips along the way. The existing anti-terrorism policies are working, even if they aren't perfect. The problem of terrorism is not mostly the absolute number of deaths and injuries it causes. Ordinary, non-terrorist harms (e.g. industrial accidents and prescription drug overdose deaths) dwarf terrorist harms in terms of direct impact. But, while other harms have many self-regulating aspects to them that naturally try to limit their impact, terrorism allowed to go unchecked can become immensely damaging and the impact on society of greater measures to prevent it can be very costly (witness the daily burdens associated with air travel security). So, decisive efforts to shut down terrorists when discovered makes a lot of sense.
Notably, however, there is almost no empirical evidence that military as opposed to criminal justice approaches work better in responding and there is some suggestive evidence that the reverse is true. Criminal justice reduces the likelihood of a cycle of retaliation and reduces distrust of the authority imposing it, and thus makes citizens more willing too cooperate in helping government to capture criminals. Criminal justice has a focus on accurately finding out who commited the crime since it operates where an ability to capture an identified and located perpetrator is a secondary consideration. It works so long as there is near universal support for authority vis-a-vis the criminals and apprehending as opposed to killing the criminal is the usually circumstance. Criminal justice obviously doesn't work when law enforcement is too weak to apprehend perpetrators who have been identified and located reliably, it doesn't work well when accurately identifying the enemy is not an important consideration, and it works less well when at least a meaningful minority of the population in the relevant communities take the side of the perpetrators rather than law enforcement. As a result, in the absence of a civil war, criminal justice is almost always the better approach for responding to domestic terrorism. But, the situation may be different in abroad or the in the midst of a civil war.
Still, even then, when local conditions favorable to a criminal justice approach exist where the perpetrators are located, it is almost always the preferred option, and if it is possible to arrest and remove someone where criminal justice approaches are not viable to face criminal justice in a place where it is viable, this is generally a preferred option to a military one. Fighting terrorism is ultimately as much about quashing future terrorist acts as seeking retribution for past ones or controlling territory, and that requires public legitimacy which is enhanced by the use of the criminal justice system which is all about making the state use of force against alleged wrongdoers appear legitimate.